SEO is an acronym for Search Engine Optimization. Simply put, websites are analyzed using a method, looking for areas that need improvement in order to capture missed opportunities for a given target market. SEO may also be used to capture opportunities you never knew existed. SEO benefit's your web presence for organic search results, organic are the search results that appear on search engines with out having to pay every time someone clicks through to your web site, or your domain being listed.
SEM an acronym for Search Engine Marketing. Search Engine Marketing comes in many forms, primarily in the form of PPC. PPC ads are most often seen on the right side of most popular search engines. PPC advertising can be a cost effective solution to increasing your companies web presence. One of the largest advantages to PPC Internet advertising is the ability to position your Domain where you want, relative to bid price for every search query.