What is difference between struts 1.3.8 and struts 2.0?

There are many differences between Struts 1.3 and Struts 2.0-

1)Action Class-

In Struts 1.3, Action Classes needs to extend an abstract base class. But in Struts 2.0, Action classes needs to implement an Action interface.

2)Thread-Safety-

In Struts 1.3, actions are singletons and thread-safe.

In Struts 2.0, action objects are instantiated for each request.

3)In Struts 1.3, actions must share same lifecycle.

In Struts 2.0, every action has different lifecycle.

4)In Struts 1.3, servlet action have dependencies on servlet API.

In Struts 2.0, these dependencies have been removed.

5)Struts 1.3 uses Action Forms to take the input.

Struts 2.0 use Action Properties for taking inputs.

As Struts 2.0 is improved version of Struts 1.3, so there are uncountable similarities between them. All the basic features are same in both.