Drupal vs JBoss Portal

When i saw the JBoss Portal 2.0 i thought about Drupal. why i use Drupal instead of Jboss portal, i can see the difference between portal and CMS but i found many features in JBoss Portal similer to Drupal. i found this discussion about the difference between JBoss Portal and drupal:

A client -- or potential client - asked me the difference between Java and PHP which was not very hard to explain even to someone who is not technical. No problem there. The next question was a bit harder and I'm not sure I answered it well. read more..