FMV vs. CG vs. MDEC

[johnjohn320]

I already posted this in the Software Forum, but no one seemed to know, so I'll try my luck here:

What exactly is the difference between Full-Motion Video, Computer Generated Cinemas and whatever the hell MDEC stands for? I know what they are kinda, for example in a Sony Playstation game the movies that look much better than there real time counterparts, but I've heard them called so many different things it makes me wonder...thanks.....