I haven't actually used Z-Brush yet, but I believe the sculpting creates more faces on the model than necessary. Although, I think it is also used to export the textures and place them on simpler models also.. Honestly the reason I haven't used it is you need a PC to get the gen-key to work.

I'm using Blender and the Unity game engine. Currently having a problem with the HUD though, can't get the joysticks to show up. :/