User blog comment:C H U N K Y/IMPORTANT MUST READ/@comment-24170167-20140108002503/@comment-5147761-20140108183615

Ok then


 * Bureaucrat: Same as admin, but have the ability to demote other admins from their rights. Can perform actions of all the ranks below.
 * Admin: Can block, promote, edit protected pages and mediawiki pages. Can perform actions of all the ranks below.
 * Rollback: Can rollback edits, which is a faster way of undoing edits. Can perform actions of all the ranks below.
 * Chatmod: Can kick and ban users from the chat.

There is also a patroller right that allows users to rollback pages and make edits as patrolled (meaning they have checked them for spam and stuff). Several users do have this right, but we don't really publicize it on the wiki.