A MORA is a JEPPESEN derived (non-official) altitude. "Route MORA values clear all reference points by 1000' in areas where the highest reference points are 5000' MSL or lower. Route MORA values clear all reference points by 2000' in areas where the highest referene points are 5001' feet MSL or higher." (Jepp Intro page 10)
I dont know about MOCA, but assume this is by JEPPESEN too,
1720. OBSTACLE CLEARANCE, PRIMARY AREA.
b.
Mountainous Areas. Except as set forth in (1) and (2) below, the minimum
obstacle clearance over terrain and manmade obstacles, within areas designated in
FAR 95 as "mountainous" will be 2000 feet. ; An area of high concentraion of mountains, there is no definite definition.
From another question on PPruNe, 'The "Y" and "Z" are just identifiers for multiple approaches based on the same navigation equipment to the same runway with diffrent procedures.' the difference seems to be in the missed approach gradients.
This is all from some research, so please correct me if im wrong,
M1995.