Look to the left, the group you're in is Doriath.
You can make a group for moderation, but unless they are a global moderator, their powers are limited to what you specify in the forums they are given authority. More than one forum, and you can have different levels of authority in each.
Global Moderators obviously moderate all sections, their powers are resticted by group, since they don't need to be put in charge of a forum, as they are in charge of them all, so to speak.
I know on RoD, what I did was made a Moderator group, and then a Global Moderator group. What the global does is obvious. When I gave members authority to moderate particular forums, I set their powers there, but I also changed their group to moderator, which by itself has no extra powers or anything different than a member, except a different color name, and a different group name/pip thing. That way one could know who the regular moderators are by their posts etc. rather than having to check the moderating list or needing to see the "forum led by" deal.
I can also choose to have the group moderator moderate a forum, that would make all members who are in that group be able to moderate that specific forum, and I still set their powers there, instead of by group.
So basically, the only groups that have instant moderations powers, without them being set by forum, are groups that have the "Make global moderator" option checked. And so far, the only groups I see here that have that, are admins and global mods.