It's also fair to note that you can give anyone access to the Admin CP by making them an Administrator, but on the forum they can retain their normal Moderator only permissions.
I've got about 5 moderators at my board which are, on the forum, simply moderators, yet I have given them access to the Admin CP by giving them "User Management" permissions.
So, when they log in to the Admin CP all they can see is user management functions.