I would not use the
word "opposites".
Philosophically, a forward involves a change of responsibility: Servlet A is handing off the request to Servlet B and saying "Here, it's yours now. I don't want it back".
An include, on the other hand happens
within the context of the first servlet. In this case, Servlet A is saying "Here, I want you to do some work on my request, but it's still mine, and give it back to me when you're done."