Well, I personally think if you are driving something, you control where it goes. I know phrases like a 'Cattle Drive' mess with that distinction, but Driving something to me is controlling it's direction with your efforts.
Ride to me is coaxing it to go where you want. You are on top of it, but you are actually at it's mercy. You can either Drive the bus, or Ride on the bus. You Ride in the back of the car, even if you tell the driver where to go.
So for me, all mechanical vehicles are Drive. All animals... because if they don't listen to you, they will go where THEY want, and you are along for the Ride.... use the Ride skill.
Piloting is then for longer planned out type vehicles like Boats/Ships/Planes/Dirigibles/etc... With those, you often plot out the course, and when you tell it to change direction the change isn't immediate. You also often can simply stop in place. You often must go port to port, and can;t just get on or off safely anywhere you like.