The process server has a built in WAS. You can build and deploy standard JEE applications on both servers this part carries over. The process server is an extended ESB.
If you want to create mediations and process flows, etc, with the full WID feature set then you require the process server. These can be created with the WebSphere Integration Developer as well. However I doubt that you where using these as they won't run on a simple WAS.
Creating mediations and process flows is totally different from the standard JEE programming.
Udo's answer is correct but I would like to add a few more things to this. WPS is superceded with the release of IBM BPM V7.5 which was released in June this year. IBM BPM is a merger of two BPM products - WPS and WebSphere Lombardi edition.Do note that both WPS and BPM 7.5 will use typically a older version of WAS (currently they use a WAS 7.
X version) while WAS 8 has been in the marketplace for a longer period of time. To do JEE stuff, you are better off using WAS as they will keep up pace with the JEE specs while WPS and BPM 7.5 lags and you will not be able to take advantage as they lag for a good period of time. WAS's focuses on JEE and providing hte base for products like WPS, WESB, WebSphere Portal etc. WPS and BPM 7.5 focus on providing a BPM platform for users to build and deploy their BPM solutions.
Hope this gives some clarity.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.