Can somebody tell me the different between web 2.0 (social network marketing) vs. Search Engine Optimization?

[gilbien03]

Search engine optimization (SEO) is the process of improving the volume and quality of traffic to a web site from search engines via "natural" ("organic" or "algorithmic") search results. Usually, the earlier a site is presented in the search results, or the higher it "ranks", the more searchers will visit that site. SEO can also target different kinds of search, including image search, local search, and industry-specific vertical search engines.

while

Web 2.0 can refer to a perceived second generation of web-based communities and hosted services — such as social-networking sites, wikis, and folksonomies — which aim to facilitate creativity, collaboration, and sharing between users.

Search Engine Optimization has a bigger scope since since social netwrok marketing is only one of the seo strategies taht can be used to improve website rankings and increase website traffic