- Both products use Eclipse UML2, an EMF-based schema, so it is possible to exchange data between them (and other products using the same UML model file format).
- Papyrus documentation is nearly non existant - IDE help is either empty or refers to external avi (sic!) files, Topcased is much better.
- There is a convient Papurys bundle install, Topcased users need to use Eclipse update.
- Topcased allows to export single or group of diagrams to several image formats, Papyrus does not.
- Both products supports meta-models and UML2 profiles.
- They are both available under Eclipse Public License (EPL).
A good Introduction to the Diagrams of UML 2.0 and some good practices are available at
http://www.agilemodeling.com/essays/umlDiagrams.htm
