The question you are asking would require an answer that would run to pages and pages, so its not really appropriate for this forum. You may find someone is willing to spend the hours required to answer this, but I reckon its unlikely. If you have more specific questions you might illicit a better response.
Read the documentation. The capabilities of both are fairly comprehensively detailed there. Download them and experiment. You'll get a feel for both, (without necessarily coming to any cast-iron conclusions).
Might I suggest though that a few of your topic headings are either unanswerable or not very useful. In particular:
Performance - you could find benchmarks that "prove" one performs better than another, but the value of benchmarks are questionable.
Architecture - Jboss's architecture is there for all to see (it being an open source product), but WebSphere's is not. You might get this sort of information by speaking to an IBM consultant.
"Power" - not sure what is meant by this term.
[ May 08, 2006: Message edited by: Paul Sturrock ]