I wouldn't know about more oc options (i'd say the non-pro model would do fine for 24/7 oc) but the main difference is indeed better support for 2 graphics cards on the Pro model. CF and SLI in x8/x8 configuration while the non-pro second slot is x4 (although not a very big issue with cards up to say HD6950, just a few percent loss compared to x8/x8).
Other differences are:
normal has ide port for old hdd/dvd + external sata II.
pro has extra internal sata III port + external sata III.
pro has an extra casefanheader.
So if you don't plan on running two graphics cards and don't need any of the extra features the normal model will suffice.
@pectin: the x1/x4/x8/x16 tells the amount of lanes with which the pci-express port is connected to the cpu or chipset. The other port is just normal pci, which is getting old by now.