Ua, Nstemi, Stemi

Studying for cardiac exam and having a hard time with the differences. This is what I think I know, can anyone else add info?
UA/ NSTEMI: no st segment or q wave changes from unstable plaque, treatment with meds, statins, nitro, ca channel blockers, o2 for nstemi
STEMI: complete occlusion, treated surgically and meds, elevated enzymes
Are they all considered varying degrees of MI?
Is that all there is for the difference? I feel like i am missing the big picture here. Thanks all