How's Freebase different from Wikipedia? From Google Base?

Wikipedia and Freebase both appeal to people who love to use and organize information. The difference lies in the way they store information. Wikipedia arranges information in the form of articles. Freebase lists facts and statistics. Freebase’s list form is good not only for people who like to glance at facts, but also for people who want to use the data to build other web sites and software. Information in article form can’t be reused in the same way (though, obviously, articles are awesome for other purposes).

In addition, the topics covered by Freebase include subjects that are too obscure for Wikipedia, which strives for notability appropriate to an encyclopedia. 

Google Base is a whole ‘nother ball of wax. The data in Freebase is all shared and collectively editable, with a single instance of each topic (as described in Question 1). Google Base, on the other hand, lets you help other people find your data, but it doesn’t provide a community editing tool nor does it attempt to reconcile data sets. It's a different animal.