The Ghetto Booty, comes with 8 total leg cuts, from the full length lower half, like the Phat Azz, to mid thigh invisible, so you can wear different length boots! Know what else is great? Free Updates, yep, the Ghetto Booty has free updates, one was already rolled out, that added the last of those leg cuts to the mid thighs.
So from a visual comparison the Phat Azz hips seem to have a bit more curve to them and the inner thigh has a cut to them. The Ghetto Booty's bum has a slight slope to it, making the curve of the butt alittle more realistic. These were differences I really like and been wanting. I like the curve of the Ghetto Booty because it gives me more of a butt. Your shape also will affect the overall look of the mesh butts, your hip length and width, as well as, the length of your legs. You will need to tweak the shape a bit from the Phat Azz shape you may use, but its not a big change, 11 body fat and 0 belly for the Ghetto booty VS. body fat 0 and belly 15 for Phat Azz. I am not one of those who has ever had a skinny minnie avatar. I always have some type of body fat and belly, until I edited my shape for mesh body parts.
There is a way to make your Phat Azz Appliers work for the Ghetto Booty, however I would be careful with those no copy, no mod appliers. The notecard that comes with the GB explains how to make them work. Hopefully designers will make appliers for the GB soon.