With a typical Google search, the objects we search for are web pages, with the connections (or graph) that help determine the pages that rise to the top primarily being links from across the web. Links, simple form, are like votes, helping Google decide which are the most popular pages to show for a particular topic.
With Facebook Graph Search, the objects we search for aren’t web pages but instead virtual representations of real world objects: people, places and things. The connections are primarily Facebook Likes. Did such-and-such a person like a particular photo? A particular doctor? A particular restaurant? Those likes are the ties that bind the information in Facebook together.
Another difference is the layers of searching or refinement that Facebook Search offers compared to Google. For example, a Google search can show you restaurants in San Francisco, a pretty much single dimensional view.
A Facebook search can show you restaurants in San Francisco liked by your friends. Or further, those liked by your friends who actually live in San Francisco, as opposed to those who live elsewhere. Or those liked by your single friends, your straight friends, your gay friends, your friends who work for a particular company….
Mark Zuckerberg, CEO of Facebook explains the new offering