The biggest diffrence is the soul grind at the heal and the trim around the muscel of the back side. This was made from Pro feed back about wanting more pure concact on certian types of shots that reqire it. for 95% or greater this wont affect the normal consumer. this was done at the request of some Pro golfers. I also read some feed back saying that Titleist tryed to maintain the Feel of the clubs Becouse its that feel that the pro's like. They're might be the slightest of feel diffrences but not much. I've been wondering the same thing and haveing not had the chance to hit them my self yet thats what i've gotten from reading verious feeds about them.