SEM has immediate results, while SEO takes time to ramp up.
You also have the freedom to turn them on or off and tweak audiences if data shows there's less traffic during a certain period of time. With SEO, it can take months or even years, before your business begins to rank on the first page of search engines.
Is Google a SEO or SEM?
SEO (search engine optimization) refers to the practice of refining your website to make it perform better in search engines like Google. SEM (search engine marketing) refers to marketing activities involving search engines, like SEO and pay-per-click (PPC), local listings on search engines, and more.
Do you need both SEO and SEM?
It is most ideal to leverage SEO and SEM together to increase quality traffic to your site. But while you are working on SEO, a well-optimized SEM strategy in place will create visibility in the meantime. Once you get the hang of SEO and SEM, your combined strategies should operate well together.