Ug! They changed their website. And not for the better, as far as I can tell. My understanding (from the earlier website) is that the Pro is quick hitch compatible - more space aroung the lower pins. From the illustration it appears that the sheet metal covers the outside of the tiller housing deck, so soil and leaves won't collect like they can (and do) on the Std unit.
I sure hope they didn't pay too much for their website "upgrade". Maybe it's a "less is more" thing ...