The only real divisions(aside from perhaps potency and power but that is just your standard population diversity) of 'spirits', that I am aware of, which Tolkien seems to present are:
- ëalar- natural discarnates(ergo the Ainur(eg Maiar, the Valar,)
- fëar- natural incarnates(ie 'souls')(ergo Men, Elves, Dwarves, )
[ July 15, 2002: Message edited by: Fingolfin of the Noldor ]