The differential will decrease the speed and increase the torque as needed for each wheel & motion adjustment. When the machine is turning the differential will supply the needed adjustments to the wheels allowing the outside wheel to move at a faster pace than the inside wheel.
The key functions of a differential are:
Transferring power coming from the transmission to the left and right axle shafts
Balancing the power accordingly to the demand of each wheel
Gears in differential further reduce the speed and increases the torque to drive the rear wheels