Across all the Halo games, we've seen many, many different varieties of Elites, most only appearing in a single game. I was wondering: according to accepted canon, are each of these varieties of Elite distinct and unique? Or is there overlap, with the differences due simply to choices made by the game designers?
For example, each game (except Halo 3) has featured some kind of invisible Elite. Some of them have shields, and some of them are called "Spec-Ops." According to canon, are the invisible Elites in Halo 1, 2, and Reach all the same or is each variety distinct?