What is the difference between the factory pattern and abstract factory?

Question

Having finally begun seriously trying to learn some basic patterns (very late in the career, but that's a different story), I'm trying to get my head around the differences between the Factory Pattern and Abstract Factory.

What are the key differences between these two patterns?

I understand that the Factory Method creates objects through inheritance and Abstract Factory does it through object composition, but from a practical point of view, I'm still having trouble visualising exactly how they each work.