Amithlon is a rather difficult thing to describe.
Imagine an ordinary PC. Imagine if someone was to take out the x86 CPU of that PC and replace it with a 680x0 that runs at Hundreds of Megahertz. Then that person was to install AmigaOS on it. You’d have something close to Amithlon. It wouldn't be able to run Speedball2, but it would be very responsive and be able to render your imagine animations blisteringly fast.
Actually, that’s a gross over-simplification. There is far more to Amithlon than meets the eye, it can do some really cool stuff. It was one of the greatest losses in Amiga history. :-(