SEO is just one discipline encompassed by SEM (Search Engine Marketing). SEM includes PPC and SEO.You can probably come up with an argument for either; but the reality is, both are vital to the team’s success. The same goes for SEO and PPC (pay-per-click). You couldn’t establish domain authority, organic brand affinity, and really, a wholly formed online presence without SEO. By the same token, you couldn’t granularly target prospects by demographic, behaviors, or keywords without PPC.