Bureaucrats grant sysop powers to elected administrators and rollback rights to trusted users. While bureaucrats are largely similar to administrators in general article editing, their opinions are almost always considered in important policy decisions that affect the whole site, as well as determining consensus in difficult cases. Other than that, the role of a bureaucrat is similar to the role of the administrator.
Curiously enough, while bureaucrats can grant sysop powers to a user, they cannot remove them. That task must be done by Wikia staff member.
Another segment of the bureaucrats' role is that their votes must be unanimous in order for a user to be approved as a sysop.