I can almost always tell my cats voices apart. I wanted to name Red Cat "Caruso" because he is always "singing" and has such incredible volume. However, when he is telling me that the litter box has been used and his human servant had better get in there and clean it NOW, he has a distinct whine.
Purdy makes a distinct "ah-oo" sound, except when he is wandering around aimlessly in the night, when he makes a sound I can't describe but is totally different than I've heard from any other cat.
Sheba, my only female, is a delicate little thing and has a small voice that is definitely soprano.