ActionForm vs. ActionFormBean

[Will Spies/Towers Perrin]

I would like to supply a new class for my Forms. When I look at the view
documentation and the example, I see that it uses an 'ActionForm' class.
However, when I look at the controller documentation it refers to an
'ActionFormBean' class. When I go and look at the struts source I find both
of these classes. Which one is it? What's the difference?