mATX, micro ATX - Whats the diff?

[Dyck15]

All these new form factors, and I havent been keeping up with the times. So what I want to know is what is the difference between all these. Is mini-ATX the same as micro-ATX...

Second thing, would an mATX board (ECS KM400-M - dont bother flaming about ECS) fit into an ATX case, or would I need to drill some screw holes.

[wayout44]

They're both the same and they will fit into any ATX case without any probs or mods.