Well essentially it works like this:
You've got the owners of the forum: Getofmeland, Teh Mite and St.Helens (is Woosaah involved? I can never remember)
Then you've got the administrators. These guys have pretty much unlimited power to edit the forum as they see fit. Currently the admins are: Getofmeland, Olyy, St. Helens, Woosaah, Ezequiel
Then you've got the super moderators who handle much of the day to day runnings of the forum. We handle deleting spam, creating new match threads, keeping threads clear of unsavoury material. Mods can do this in any sub forum on the board. Currently the moderators are: Draggs, ORothlain, Cymro, Darwin, Feicarsinn, Nickdnz and RC.
TRF Legends are usually former members of staff who for whatever reason have decided that they aren't going to be involved in the day to day running of the forum. The most notable include Teh Mite, CA Iversen, An Tarbh and Steve-o.
There are other mods who only have jurisdiction over certain sub forums. An example is best_fullback who is a mod for the Universtas Rugbeia.
That's about the long and short of it I guess.