We work on Joomla adn it is nice ..
Main differences are as under
1. Drupal use smarty template where as on the other hand
Joomla dose not
2. Joomla uses plugin and modules whereas Drupl has module only
3. In drupal php code can be written directly whereas in
Joomla you need to install plugin for php support
4.Drupal is Fast than Joomla