Question: what is the difference between 4 up and 4 down?
Answer: 4x4 low means low speed, similar to an ATV, permits to go in rocky terrain with very unequal bumps. The engine will have tremendous torque in low 4x4 to be able to climb over a stiff rock. High 4x4 is for regular road condition if you may encounter a patch of Ice of are in a snow storm.