What is the difference between SEO and SEM? Does it matter?
It might not matter to some people, but there is a subtle difference. SEO stands for search engine optimization and usually refers to the process of writing web page content so that it stands a better chance of ranking in the search engines. If your web pages rank in the search engines, then that’s free traffic for your website. You don’t pay for that traffic.
Search engine marketing, or SEM, refers to any form of search engine marketing and that includes the aforementioned SEO. But it doesn’t stop with SEO.
Search engine marketing most often refers to organic search (SEO) and paid search (PPC). But it could also include other forms of search engine marketing including display advertising, paid placement services, link building, search query sponsorships, or other services depending on the search engine. But most Internet marketers use the term SEM to refer to SEO and PPC.
Typically, a search engine marketing campaign consists of a combination of SEO and paid search strategies. A search engine marketer may find himself managing a pay-per-click campaign simultaneously with a link building campaign. And that may include guest blogging, article marketing, and even some on-site content management.
Most of these terms overlap in some way, but it helps to understand what your search optimization team is saying when they communicate with you. I hope this helps clarify things a bit.