Bureaucrats are senior editors. In addition to the Administrator rank and the Administrator abilities, they also gain the ability to grant limited user rights. The demotion of a Bureaucrat is not done without a community discussion unless it is absolutely necessary.
Administrators are editors who are entrusted with powerful tools that help maintain and manage the wiki. They have the ability to issue blocks to troublesome editors, delete and move pages, and revert vandalism and edits not made in good faith with the rollback tool. They are authorized to handle site issues with the tools at their disposal to the best of their ability.
Content Moderators are responsible for locating and erasing vandalism, and for keeping blogs, articles, and other pages clean, along with checking edits to make sure they are contributive and not vandalism. In emergencies, they can change page protection.
Discussions moderators are responsible for activity in all discussions threads and comments. They keep discussions forums and comments a safe place and can delete, edit, highlight, and lock threads, and can edit and delete comments.
Rollbacks are responsible for organising the wiki through reverting bad edits quickly.