Both the apps say they provide you with your PGA Certified Handicap. I believe the PGA and Diablo Golf were in a lawsuit that was finally settled and Diablo can offer your Handicap now.
Like I said earlier Diablo Golf is basic. You find the course you played drop in your score in total. There are social functions as well.
Grint you can use on the course, to keep track of your score by hole, as well as number of puts, placement of tee shot, and penalty strokes. The paid version it also acts as a GPS. While having still having the social functions of either. I look at the Grint as a way to really help you understand your game, but not sure if it is worth it for a hack like me.