What is the difference between SEM and SEO?

AKA Organic Versus Paid Traffic

Ever wondered what’s the difference between Search Engine Optimisation and Search Engine Marketing?

The easy, and short answer is: SEO is free you don’t have to pay for SEO and you do for SEM. The long answer is a little more complicated (always is!), however, despite having similar features, they have completely different strategies and approaches. HammaJack’s Ian Hammond has tried to outline a few of the key differences in this article.

What does SEO and SEM mean?

If you run a business, you may have been approached by someone telling you “you need to have someone managing your SEO, SEM etc etc”. You might have even taken steps to try and improve your organic findability or taken up a free Google Ads voucher and created ads.

We often get asked about our approach, and specifically, some people ask ‘what does this include’, or ‘how much does it cost’.

It’s a cop out, but, depending on what you’re after, and your individual circumstances, it’s never exactly the same.  


There’s some debate as to how SEM fits with SEO. You could even argue “optimisation” includes “marketing” or maybe that “marketing” incorporates “optimisation” … potato, potato. In my opinion it’s semantic nonsense. They are two separate things. Yes — closely related perhaps (after all, they involve search engines and keywords!) — but here at HammaJack we treat them as two distinct practices.

SEO aka Search Engine Optimisation

SEO stands for Search Engine Optimisation.

In its simplest terms, it’s the process of being found on Google, or other search engines (there are more than you think) without having to pay them directly for it.

“Optimisation" gives the impression that it’s not a set and forget type of thing — and this is true. You have to stay on top of your SEO — as your competitors are trying to rank for the same keywords that you are.

SEM aka Search Engine Marketing

SEM stands for Search Engine Marketing.

It’s the advertisement that appears in the search engine results page. With so much competition for keywords on search engines, businesses can pay to appear at the top of those searches.

What’s involved in SEO?

When we are explaining SEO, we try to think about two main indicators: Human and Non-human indicators.

We developed this as a way of reminding ourselves that SEO is based on an algorithm - a maths equation, but - there are indicators that we can see, and can try and improve - we call there Human. And then there are other factors that we cannot immediately see – yet they still impact on your findability, we call these non-human.

Human indicators


Put simply, human SEO indicators are ones that you and I can see and experience on a website.

Things like:

  • Is the copy engaging?

  • Does it make sense?

  • Is it well written, or well put together?

  • Does it work on mobile?

  • Can I read it?

  • Does it tell me what I’m looking for?

Ultimately, better sites are more engaging and get rewarded by search engines.

Apart from readability, other ‘human’ aspects that will harm your findability with search engines are page speed and site’s not being optimised for mobiles.

Non-human indicators

The other aspect, probably more important than human factors, and that usually takes a little longer to understand, is non-human factors. These are things that tell search engines some sites are better than others. You won’t necessarily notice these things when you click on a website — but search engines certainly do.

Things like:

  • Distribution of content across HTML

  • High-quality Backlinks

  • Code and image sizes

  • Alt-text images.

The good news, is that there’s a bunch of third party tools that will help tell you whether your non-human SEO is any good, and therefore — how you can improve it.

Take a look at:

What’s involved in SEM?

When we think of SEM, we think about auctions, ad relevance, quality scores and more. The way in which search engines sell you space at the top, side and bottom of the search engine results page is incredibly complex and takes time and tests to get it right.


SEM is built around Auctions, and how much you are prepared to pay for a click, or for an impression (being seen). This is important, as like a house that a few people want, demand will drive up price.

It also gives you an insight into how to win at SEM (it’s not hard, duh, you just have to find the words that no one else is prepared to bid on, or bid more than anyone else).

Easy, right?

Well. Not quite.

Quality Scores (QS)

Remember that search engines care about ‘experience’. It’s the same with SEM. They have tethered their auction to a “Quality Score”, which is essentially how good your ad meets the intent of the search, and the the experience they had.

Things that will impact the Quality Score:

  • Click Through Rate

  • Quality of Advertisement (as in, the copy and structure)

  • Landing page experience

Given the nature of SEM, nailing the intent of certain keywords, especially broad, or more general keywords, or ones that have lots of meaning can be difficult. Which is why, you need to try and find that balance where you find relevant keywords, with traffic.

An Example:

If you are say, trying to rank for HR, bidding on HR is going to be difficult to get a high QS. As you would imagine people searching for “HR”, could be looking for a multitude of things.

You can see how “HR Agency in Melbourne”is going to be more relevant than “HR”, and “HR Agency for cafes and bars”, might even be more relevant.

The trick is making sure you have your account set up in a way that allows you to keep finding those relevant keywords, and that the structure allows you to maintain a high quality score.

But what if you have a low QS? Low QS means you will pay more. Work hard to build a high QS and get more relevant traffic and you will pay less.

Other Features

Because you can use search engine’s digital memory, you can start to utilise different audiences and behaviours to narrow who you are targeting. For instance, would you pay more or less for someone who has been to your site previously? Or perhaps, someone who has clicked on one particular ad (for long-tail keywords) and then searched for you — how much extra would you pay to make sure you appear at the top of the search results page.

And then that’s not to mention all the things you can do with retargeting using the Google display network, YouTube etc etc. But that’s for another day.

How much does SEO and SEM cost?

SEO is cheap...Right?

Eventually! It’ll cost you nothing. Exactly! It’ll just sit there and bring you in traffic. You won’t have to do a thing. But, before you get there, you have to chip in:

  • Content writing: You can do it yourself, or hire a writer who can write for SEO — perhaps hundreds, or even thousands. Try not to go for the freelancer “we’ll get your site number one on Google within 60 days”. Too often it’s just stuffed with keywords.

  • Backlinking: A good and well thought out backlinking strategy is worth its weight in gold. Or you can risk paying someone to help you with it. Min $900 per month.

  • Development and design: Site a little slow? Images too large? You might want to reach out to your dev team and have them make some changes.

  • Ongoing blogs and site content: ^ see above. If you feel comfortable writing blog content and making site changes, then it’s free. But, it takes a certain skill to make sure you’re bringing the right kind of SEO value to your site. And then, remember, people don’t just want to read words, content includes images and videos.

SEM can be expensive?

Yep - you betcha. SEM can be really expensive. But, unlike SEO, you’ll know exactly how much you spent, and be able to see see immediate returns. So the question becomes, not — how much money did it break me, but how much money did it make me?

This is why it’s incredibly important to make sure you have tracked and tagged your site up, and know how much value your site visitors make, and have the potential to make you.

So yes, you can pay a lot on SEM. But, if you are — you’d want to make sure you’re making a heap back too!

Most Important Point

We hope that you agree tha SEM and SEO are two very different things — but, also you can see how each has their place in any business looking to drive traffic to its site and that each area has a number of strategies and intricacies that should be considered.

Also — what we’ve outlined above, is that the best approach for SEO and SEM is to take a data-driven approach to what’s working, and what’s not. If you’re interested in how we might be able to help you with your own SEO and SEM strategies, please don’t hesitate to reach out.