Oh, okay. I don't really remember what ainur or vala are. I've heard of the second not the first. Weren't the Valar semi-deities? I read silmarrion years ago but I don't really remember it. Is Irmo a character in it?
Yes they are semi-deities. "Ainur" are all and "Valar" are the ones who walk on Arda (I think, I never read the Silmarillion, but I have to hehe). Irmo is a Ainur on Arda, so he is a Vala. Just google him and you will find all infos.