Well, one difference is the crankshaft. It is 212cc but uses a 196cc taper, so you can use many of your BS components with it, like a regular ARC flywheel.
As for build quality, unless I go out and buy 10 motors, put micrometers on each one, I have no hard data. If you want hard data, call them and ask, or go over to bob's forum and talk to guys who have bought them at this point. They just started shipping these about a week ago. There are very few on the market as of yet.
So to answer your question: We have no hard data. That will come as times goes on. If you want hard data either wait until enough builders have built enough of them or call them and ask them directly for specific differences. That's on you not us.