Abstract factory vs Factory Pattern

Abstract Factory is used to create a set of abstractions. 

You use the Factory Method to create and hide the creation of one object of a set of classes that implement the same interface.

In very simple terms: think about Abstract Factory like a set of several Factory Methods.

You use an Abstract Factory for something like this:

Software Abstraction Layer
http://msdn.microsoft.com/en-us/library/cc304370.aspx