SEO vs. SEM: Differences in Techniques, Costs, & Results

Asif Ali

Dec 21, 202316 min read


Many online experiences start with a search engine.

This means search engines like Google and Bing are great for getting your products or services in front of potential customers. 

In this article, we’ll explain everything about search engine marketing (SEM), its different components, and how it all works.

But first, let’s start by briefly comparing it to search engine optimization (SEO).

SEO vs. SEM: What’s the Difference?

Google something, and you’ll typically see two types of results: 

  • Organic search results: Unpaid listings that appear on a search engine results page (SERP). They appear because the search engine’s algorithm has determined they’re relevant and helpful to the user’s search query.
  • Paid search results: Paid advertisements that appear on the SERP. These results typically feature a “Sponsored” or “Ad” tag to distinguish them from organic results. Businesses using search ads pay a fee each time the ad is clicked, so paid search results are often called pay-per-click (PPC) ads.

Here’s a SERP with both types of results:

Google SERP with paid and organic search results

SEO focuses solely on improving organic search results.

But SEM includes both paid and organic search results. So, SEO is a subset of SEM.

SEM includes SEO and PPC

Now, let’s break down SEO vs. SEM in detail.

What Is SEO?

SEO is the process of improving your website to enhance its organic visibility on SERPs. 

This typically includes creating and optimizing pages that address users’ search intent (the reason behind a search) for specific queries. 

The "what," "why," and "how" of SEO

Pages with the most helpful and relevant content are more likely to appear in the first few organic search results. These are the results users see first.

But helpful content alone isn’t enough. It must be understandable to the bots (also called spiders and crawlers) that search engines use to crawl sites.

Here’s how the process generally works for Google:

  1. You publish or update a page on your website
  2. Google crawls your website and finds the new or updated page
  3. Google (hopefully)indexes your page
  4. Google (hopefully) ranks it as a search result for a certain query (or set of queries), so users can find it
How search engines work

To determine where a page should rank in search results, search engines use algorithms that evaluate various factors. 

And SEO tactics ensure that a website aligns with those search ranking factors. To increase the chance of ranking higher on SERPs. 

Some of Google’s broader and more consistent ranking factors include:

  • Relevance: Does the content align with the user’s search query and provide the most helpful answer possible?
  • Quality: Is the content trustworthy and authoritative? Search engines may assess this by looking at factors like backlinks (links from other reputable websites that point to your site) and the depth of the content.
  • User experience: How easy is the website to use? Things like site speed, mobile-friendliness, and clear navigation play a role.

Now, there are many SEO tactics. These can be grouped into three broad categories: on-page SEO, off-page SEO, and technical SEO.

Here’s an overview of each:

On-Page SEO

On-page SEO involves optimizing your webpage content for search engines. But it’s really about making those pages more helpful for users—not just search engines. 

You can use Semrush’s On Page SEO Checker to improve your site’s on-page SEO.

Open the tool, enter your domain, and click “Get ideas.”

On Page SEO Checker search bar

Follow the steps to complete the configuration. Check out our in-depth setup guide if you need help with this.

The tool will then audit your pages. Once done, it’ll take you to the report. 

Check the “TOP pages to optimization” widget. And click “# ideas” next to any page. 

"TOP pages to optimize" section of the overview report

You’ll then be taken to the “Optimization Ideas” tab for that selected page.

"Optimization Ideas" table with categories and recommendations highlighted

Follow the recommendations to improve your site’s on-page SEO.

Now, let’s go over some common on-page SEO techniques to ensure your webpage content is as good as it can be from the start:

1. Create High-Quality, Authoritative Content

Google prioritizes content that’s helpful and reliable. And a good way to ensure you’re meeting a high content quality standard is to consider Google’s Experience, Expertise, Authoritativeness, and Trust (E-E-A-T) guidelines that quality raters use when evaluating search results.

What E-E-A-T stands for

But quality isn’t just about credibility. It also means ensuring your content is unique.

Search engines value original content and tend to rank it higher in search results.

Further reading: How to Improve Your Site’s E-E-A-T

2. Optimize for Relevant Keywords

Keywords are the terms or phrases users input into search engines to find information. 

Effective on-page SEO requires two steps:

  • Identifying the most relevant keywords for your content
  • Incorporating them in a natural way

Semrush’s Keyword Magic Tool can help you identify good keywords. 

Open the tool, enter a seed keyword (a broad keyword related to your product or business), and enter “Search.”

"cookie recipes" entered into the Keyword Magic Tool search bar

You’ll find many keyword ideas here—plus data points like search volume, keyword difficulty (a measure of how difficult it will be to rank in the top 10 for a given keyword), and search intent.

A ist of related keywords to "cookie recipes"

Select the keywords that are most relevant to your business, click the “+ Add to list” button, and name your list.

Adding selected keywords to the list

Then click the checkmark to add all your selected keywords to the Keyword Strategy Builder, where keywords will be automatically grouped. From there, you can manage and analyze all your keywords centrally.

Once you’ve identified keywords you want to target, you’ll then need to incorporate them into your content. By including them in headings and subheadings, body copy, etc.

3. Write Descriptive Meta Tags

Meta tags are elements of a page’s HTML code that help search engines understand what the page is about. And may influence how your page appears in search results.

One important type of meta tag is the title tag (sometimes called the meta title). It appears as the title of your page on SERPs. And it’s something search engines consider for rankings and can also influence whether users click through to your site.

Here’s what a title tag looks like:

A title tag on SERP that reads "The best running shoes for 2023 - tried and tested"

Another type of meta tag is the meta description, which summarizes the page’s content. Like this: 

A meta description on SERP that reads "Keep dry and protected in a pair of stylish women's rain boots from Joules. Browse various styles, heights & prints, online today."

While it doesn’t affect your rankings, a compelling meta meta description can influence a user to click on your search result over a competitor’s.

Internal links connect various pages within your website, creating a cohesive structure.

Strategically linking related content pieces helps users navigate your site. And encourages deeper engagement.

These links also help search engine bots discover, crawl, and (hopefully) index your site’s pages.

How Google discovers pages

4. Maintain Clear URLs

A URL should be descriptive and intuitive, offering both users and search engines insight into the page’s content.

For instance, a URL like “” immediately conveys the topic of the page compared to one with unclear characters.

A clear URL vs an unclear URL

Off-Page SEO

Off-page SEO includes all the activities you perform outside of your website to boost its visibility and rankings on search engines. 

Here are some common off-page SEO techniques:

Backlinks are links from other websites that point to your site. They’re also called inbound links.

Think of each backlink as a vote of confidence in your site. When reputable and relevant sites link to yours, search engines take note. 

And sites with a stronger backlink profile are generally considered more trustworthy and authoritative—meaning they often rank higher on SERPs.

A page that links to another site passes authority to that site

But it’s not just the number of backlinks that matters. It’s also the quality of the domain they come from. 

A few links from one or two high-authority sites can be more beneficial than many links from lesser-known sites or those with less credibility.

You can use Semrush’s Link Building Tool to discover link-building opportunities based on your target keywords and competing sites.

Open the tool, enter your domain, and click “Start Link Building.”

"" entered into the Link Building Tool search bar

In the next steps, you’ll be prompted to enter your top competitors and target keywords. You can follow our in-depth setup guide to configure the Link Building Tool.

Once done, you’ll see this screen:

Link Building Tool overview dashboard

Go to the “Prospects” tab. Review all the URLs and click “To In Progress” next to each of the sites you want to get backlinks from.

"Prospects" table in Link Building Tool

Next, head over to the “In Progress” tab. You’ll be able to create and manage all your link-building email outreach activities from here. 

“In Progress” tab

You may need to test out different outreach tactics before you find one that works. And with a little patience, you can start getting more backlinks to your website.

2. Invest in Local SEO

Local SEO focuses on optimizing a business’s online presence to attract customers from local searches.

Here’s an example of how local listings appears on Google:

Local listings on Google for "food near me" query

Google Business Profile is a key part of local SEO on Google. And because making improvements to it is something that occurs outside of your own site, it falls under off-page SEO.

Optimizing your Google Business Profile can increase your visibility for local searches. And it also displays your reviews. Which act like endorsements from the community.

3. Write Guest Blog Posts

Publishing a guest blog post on a third-party website won’t directly affect your site’s rankings. 

But this tactic can still help your SEO efforts—especially if the website in question is a reputable one in your industry.

Guest blogging positions you as an expert in your field and (sometimes) provides opportunities to link back to your site.

But you should always prioritize quality and relevance when choosing platforms for guest blogging.

For example here’s an example of a guest post written by Semrush’s Marcus Tober for Adweek:

A guest post written by Marcus Tober for Adweek

4. Gain Brand Mentions

Brand mentions are when other websites talk about or reference your brand, even if they don’t directly link back to your site.

Search engines are always listening to these digital conversations. So, when your brand gets mentioned by an authoritative or popular website, it acts as a signal that reinforces your brand’s reputation and authority.

Over time, consistent and positive brand mentions can contribute to a stronger online presence. Which may lead search engines to rank your content higher in search results.

You can monitor your brand mentions using the Media Monitoring app. Just enter your brand name and create a project.

Creating a new project in Media Monitoring app

You’ll get a report listing your most recent mentions. You can also see what percentage of those mentions are positive, negative, and neutral.

Media Monitoring report dashboard, showing a list of positive, negative, and neutral mentions, number of mentions over time and summary of brand sentiment

Technical SEO

Technical SEO ensures your site is optimized for search engines and to improve the user experience. Think of it as the under-the-hood work.

You can check your site for technical SEO issues using Site Audit.

You’ll first need to create a project for your domain. Follow our in-depth setup guide if you need help with the configuration.

Once the website is crawled, you’ll see this “Overview” report:

Site Audit "Overview" report

Navigate to the “Issues” tab. 

"Issues" table in Site Audit tool

Review all the technical issues your website has. Then, address them one by one.

You can click “Why and how to fix” to learn more about each issue. And what it takes to fix the issue.

Now, let’s go over how you can focus on avoiding these types of issues from the beginning.

1. Ensure Your Site Is Mobile-Friendly

Most searches occur on mobile devices now. So, having a mobile-friendly website is no longer optional.

You must ensure your site looks and performs seamlessly on smartphones and tablets. Like this:

A website shown on mobile, tablet and desktop screen sizes

To ensure your site looks great on all device types, it’s best to use responsive design. 

2. Craft a Clear XML Sitemap

Think of an extensible markup language (XML) sitemap as a roadmap for search engines. It lists all the important pages on your website and helps search engines find new or updated content.

Here’s an example of what an XML sitemap looks like:

XML sitemap

You can easily create, check, and submit an XML sitemap for your site. Which helps search engines more easily crawl your site’s pages. To help with indexing.

3. Use HTTPS

Hypertext transfer protocol secure (HTTPS) is the secure version of HTTP and ensures that the data shared between your website and visitors is encrypted. 

Hypertext transfer protocol secure (HTTPS)

By migrating your site from HTTP to HTTPS, you can safeguard your users’ data. And signal to search engines that your site is trustworthy.

Search engines give preference to secure sites.

4. Optimize Your Core Web Vitals

The Core Web Vitals (CWV) are a set of metrics to measure user experience on your site.

They focus on loading performance, interactivity, and visual stability. And because they’re centered on page experience, they can affect your rankings.

Specifically, those metrics are:

  • Largest Contentful Paint (LCP): This measures how long it takes for your page’s main content to load. Google recommends this be 2.5 seconds or less. 
  • First Input Delay (FID): This measures how long it takes before a user is able to interact with your page. This metric should be 100 milliseconds or fewer. Note that this will be replaced with a metric called Interaction to Next Paint (INP) in March 2024.
  • Cumulative Layout Shift (CLS): This measures how often users experience shifts in your page’s layout. Aim for 0.1 or less.
Core Web Vitals metrics explained

5. Manage Redirects and Address Errors

You can ensure smooth navigation across your site and minimize dead ends by setting up proper redirects

Redirects automatically send users from one URL to another. You can set them up for pages that have been deleted or moved to a new URL. 

A proper redirect plan helps you avoid 404 errors, which occur when a page doesn’t exist or can’t be found.

It’s generally best to use a 301 redirect for a permanent move and a 302 redirect for a temporary move.

What Is SEM?

Search engine marketing is a broad term that includes everything about SEO we’ve discussed so far. And it also encompasses the PPC search ads you see on many SERPs.

PPC search ads for "puppy food" on Google's SERP

You’ll see search PPC search ads in two distinct formats.

One is text-based. These ads often resemble organic search results but with a “Sponsored” or “Ad” label. 

The other type is shopping ads that showcase product images, prices, and more.

Shopping ads for "headphones" on Google's SERP

To better understand the SEM vs. SEO comparison, let’s look at the key components of paid search ads:

PPC Keyword Research

Keyword research in PPC involves identifying the keywords that are relevant to your business and aligned with your campaign goals. 

By focusing on the right keywords and targeting criteria (more on that in a moment), you can ensure your ads reach the right audiences.

Semrush’s Keyword Magic Tool can help you find the best keywords for your campaign. 

Just follow the same process we outlined earlier. But focus on keywords that align with what you want to achieve. 

For instance, if you own a running shoe store in New York City, you might want your ad to appear when someone in New York City searches the keywords “buy running shoes” or “sports footwear sale.” 

PPC Bidding

With PPC, you decide how much you’re willing to pay for a click on your ad. This is called a bid. 

Here’s an example showing the total bid range for target keywords in Google Ads:

Total bid range for target keywords in Google Ads

Bid management involves strategically setting this amount to maximize your return on investment (ROI). It’s a balance between wanting your ad to appear prominently in the search results and ensuring you don’t overspend. 

For instance, if you sell handmade shoes and set a bid of $1, you’re telling the search engine you’re willing to pay up to $1 each time someone clicks your ad. 

PPC Audience Targeting

For PPC search ads, audience targeting lets you specify certain criteria for who you want your ads to show for.

For example, if you run a local bakery in New York, you might target people within a 10-mile radius who’ve shown an interest in baked goods. 

This way, you’re not wasting money on ads shown to someone in California or someone who’s only interested in fitness products.

Here’s an example of some of the interest-based targeting options in Google Ads:

Audience segments window in in Google Ads

PPC Ad Creation

PPC search ads need to communicate your message quickly and effectively. Which involves crafting a catchy headline, a relevant description, and a clear call to action (CTA).

Here’s an example of an attention-grabbing search ad for the keyword “salesforce alternative.” Note the interesting headline, info-packed description, and clear CTA:

Freshworks's PPC search ad for “salesforce alternative" query

When writing search ad copy, a good idea is to look at your competitors and learn from their ads.

Semrush’s Advertising Research tool can help. Simply enter a competitor’s domain and navigate to the “Ads Copies” tab and check out their ads.

"Ads Copies" tab for "" in Advertising Research tool

Analyze the emotional hooks they’re using and the keywords they’re targeting. 

"Keywords that trigger this ad to show" table in Advertising Research

If any of this messaging strikes you as particularly effective, consider testing a similar approach.

PPC Ad Assets

Previously known as ad extensions, assets are additional elements you can add to your Google PPC search ads to provide users with more information.

Sitelink assets shown below Sleepopolls' search ad

They come in various forms, such as a clickable call option:

A clickable call option asset under search ad

Or a business address:

A business address asset under search ad

If you run a spa, a location asset would show searchers your exact address. And a call asset would offer a direct line to book appointments.

Incorporating these assets can help your ads drive more conversions.

What’s the Cost of SEO vs. SEM?

The relative costs of SEO and SEM can vary significantly.

SEO may be unpaid, but it’s not necessarily free. Doing SEO the right way means investing in website optimization, content production, backlink outreach, and SEO tools.

How much does that add up to? It depends. 

A local business will likely spend less on SEO than a multinational company due to differing goals and competition levels. 

According to Backlinko data from 2019, the average cost of SEO services at that time was about $500 per month. Just note that your budget may differ greatly depending on your goals.

Average cost of SEO services, according to Backlinko study

SEM, on the other hand, includes all SEO expenses plus what you allocate for creating and managing PPC campaigns.

One study found that typical PPC costs can range from $100 to $10,000 per month.

This cost difference means that many businesses with a limited budget might be tempted to stick to organic tactics in the early stages of growth. 

But keep in mind that paid campaigns tend to generate results much faster, which can be crucial for companies that need to start driving more business.

How Long Does It Take to See SEM Results? 

Results aren’t instant with SEO. After making website changes or adding new content, it can take months to see a rise in organic rankings and traffic. 

PPC is quicker. Once a campaign is set up and approved, your ads can appear immediately. 

But quick visibility doesn’t always mean instant success. Your ad might get clicks immediately, but refining it to achieve the best results can take some time.

In short, SEO is a slow build with a potentially good payoff. And PPC offers immediate results that can be honed and improved over time.

An effective SEM strategy usually incorporates both to better address short- and long-term goals. And different types of search intent.

Which SEM Practice Is Right for You?

Both SEM practices have their advantages and use cases. Which one you should focus on largely depends on your goals, budget, and timeline.

Here’s when to think about prioritizing SEO:

  • When you have a limited budget
  • When you’re planning for the long term
  • When you’re targeting informational intent keywords
  • When you want to build your reputation and credibility 

And here’s when to think about prioritizing PPC:

  • When you want immediate results
  • When you’re targeting transactional keywords
  • When you want precise budget and targeting control
  • When you want measurable and quick results

But you should ideally have a comprehensive SEM strategy that incorporates both SEO and paid search to help you meet your immediate goals while still setting the stage for future success.

Integrated SEM strategy incorporates SEO and paid search practices

Build an Integrated SEM Strategy

If you want to boost online visibility for your business, you need a robust SEM approach that draws on both paid and unpaid tactics.

Start by assessing your needs, goals, and budget. 

Then, build an integrated search engine marketing plan where SEO and PPC complement each other to help you achieve your goals.

And remember, keyword research is at the heart of both SEO and PPC efforts. So, try Semrush's Keyword Magic Tool to find the most rewarding keywords for your organic and paid campaigns.

Author Photo
Asif is a content marketing specialist with over eight years of experience. While working at agencies and startups, he has helped brands drive millions in sales through full-funnel inbound marketing campaigns.
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