Anyone can revert vandalism and bad-faith edits, but it takes a couple of clicks in the page history to get it done. Users with the "rollback" permission are able to undo bad edits with one click, by using the rollback link on diff pages, user contributions list, or the list of recent changes.
It is important to note that admins already have rollback rights by default. Users with rollback rights are just users who are not necessarily an admin.
Chat moderators are users who have chat moderator status in chat in order to moderate a wiki's chat room. They are able to 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 removes "Banned from chat" at Special:UserRights.