Found an older post on a different forum.... MC apparently is the "maximum capacity" version.
Regular BC-25 you can use different coin types in each hopper. When one hopper runs empty, the machine shuts down. (not sure if you can run a regular BC-25 in MC mode or not. My BC-12 has that option via dip switchs).
BC-25MC is only a single type of coin in the entire machine, and if a hopper runs empty it just moves to the next one until all of them run dry.
-Hans