You can tell who does what by the colour of their username.
Administrators (or sysops)
have all privileges from the Discussions Moderator and Content Moderator groups. They can block users who are vandalizing the wiki from editing and other actions, and they can grant and revoke both the Chat Moderator and Discussion Moderator rights. Also they can edit the community's skin and format and whitelisted MediaWiki pages.
can undo bad edits with one click, by using the rollback link on diff pages, user contributions list, or the list of recent changes. Content Moderators and admins already have rollback rights by default.
are one level 'up' from administrators. Bureaucrats only have the ability to manipulate user rights, as well as block and unblock users, so this right is generally used in addition to the administrator group. They have the ability to promote and revoke rollback, Content Moderator and administrator rights as well as appointing new bureaucrats. While they cannot directly revoke another user's bureaucrat status, they can revoke their own.
A "bot" is any automated process, program, or script that makes it easier for a user to make tedious or repetitive edits and actions on a community. They are (real but fake) accounts that are run by a Wiki member.
are users who have chat moderator status in chat to moderate a community's chat room. They can block users from chat, which will kick a user out of the chat and ban them from returning until a chat moderator or an admin unbans them from the users' contributions page, or if the ban expires.
are users who have additional tools available to moderate specific parts of the community. These tools are:
Deleting and moving protected pages
Deleting and moving files
Undeleting pages and files
Protecting and unprotecting pages
Patrol pages if the community has the RecentChanges patrol feature enabled