Your links do not work for me.
The extreme 4 is a full sized ATX board with 7 expansion slots.
The M is a smaller micro-ATX board with 4 expansion slots.
Most of us only need a single pci-e expansion slot for a graphics card.
If you are interested in triple monitor gaming using sli, then the full atx board might be good.
Anything less, and the Matx will be fine. I happen to like Matx because you can put it in some really nice smaller cases.