Just some years before we started our website - http://www.drupal-web-developers.com/
At that time onwards I am comparing the features of Drupal and Joomla and now I am here to exlore you all about the main advantages of Drupal which cannot be fullfilled by Joomla..
1. Drupal is a 'developer's' CMS. You'll find that the drupal community is packed full of php geeks, but you'll rarely find good designers. That's because drupal offers incredible possibilities in terms of what you can do with modifying the code. My solution has always been: just build your own themes.
2. Drupal was designed more for programmers, site developers & sysadmins (read: steeper learning curve).
3. Editing in Drupal is as simple as logging in, clicking a pencil icon, making your changes, and saving.
4. When we develop the sites in the Drupal - CMS - then the site will be 100% secured where in Joomla this feature is 0%.
5. There is no word "impossible" in drupal - where in Joomla we have to end up our development forcely in many places due to lack of support and extension.
I hope this will help you all to know about the Drupal - an 2008 best CMS award winner.