Not an expert but I will give it a shot. Self bows have no glass, and I think no backing. I could be wrong on the backing, but mostly they are just wood. Long bows are long and have narrow and deep limbs. Flat bows have thinner wider limbs like curves, but with a longbow shape. Hybrids are whatever you want to call them, and it depends on if you are a purist longbow type. They are called hybrid, longbow, semi-recurve, R/D (or is it D/R) long bow……….. , but typically the hybrids are more a R/D flat bow or semi-recurve. Where to draw the line between the R/D long bow and hybrid is hard to always say from what I read. Some take into account the grip and some only the limb. If it is a three piece bow it is a hybrid, or maybe R/D flat bow due to the limb shape required to bolt it on a riser.
I call anything a longbow that is not a recurve. That keeps it simple. My Firefly is a hybrid, but you could call it a R/D flat bow. My MOAB I see as a R/D longbow. The Lost Creek is a hybrid and I could be talked into a semi-recuver on that one.