Purely cosmetic; gameplay will be the same, but your character will look different.
Regarding cosmetics, I was also wondering. Will we be able to have some more customization kind of like how we can change body parts in OPP, for example, to start the game with a flat/bigger chest or butt, or already have swelled lips at the beginning of the game.
I would be very interested in things like that. If that is feasible?