Difference between h:button and h:commandButton

Question

In JSF 2, what is the difference between h:button and h:commandButton ?

Answer 1

Here is what the JSF javadocs have to say about the commandButton action attribute:

MethodExpression representing the application action to invoke when this component is activated by the user. The expression must evaluate to a public method that takes no parameters, and returns an Object (the toString() of which is called to derive the logical outcome) which is passed to the NavigationHandler for this application.

It would be illuminating to me if anyone can explain what that has to do with any of the answers on this page. It seems pretty clear that action refers to some page's filename and not a method.