Drupal is one of the best CMS (content management systems) around. It is originally created by Dries Buyteart, now being developed by large number of drupal community users. It runs on PHP and uses MySQL (other database management systems are supported too) as a back-end for storing data, settings, permissions and other necessary things for running a drupal based web site. Drupal offers many features: create posts, static pages, add menu items (primary and/or secondary menu), supports blocks (or called widgets on wordpress), users and user management (add, edit users) with powerful permission system, rss feeds and many others. It also supports theme system where you can easily change the look of the website, there are many free and professional templates available and it is very easy to create drupal theme. Other feature worth noting is the extension system (modules). Modules add new features and functionality to drupal and there are many free available in drupal module directory. Many popular websites use drupal, like the whitehouse.gov, many fan sites etc.
Drupal on Bluehost
Bluehost supports PHP and MySQL so there would be no problem installing drupal on your bluehost account. You can install it via fantastico one click installer cpanel tool or manually by uploading package files and setting up databases and installation, which way you prefer. .Htaccess and custom php.ini are supported by blue host if you need to further customize some settings like register_globals and/or enable clean (SEO) urls.