what is mega drive and hyper drive mix'n"match

[anotherfixit]

A dumb quuestion, but google seems to useless for this one.

some of my components say hyperdrive, some say megadrive.

What do they specifically mean, can I mix n match ? Will I have chain issues. I pressume hyper drive is the "spike and groove" system to enable easy changes ?

this is on a 3x9 MTB bike deore rear derailleur (RD), deoere hollowtech II crank 48T (just fitted as upgrade), acera FD, about to be replaced with a deoere FD (upgrade).