Power steering rack V.s Rack & pinion
 

What's the difference if any between the Power steering rack and the Rack & Pinion? What role do they play in the steering?

Thanks

They're one and the same. The r&p converts the spinning of the steering wheel into a lateral motion that causes the front wheels to move from one side to the other.

The older cars didn't have power assisted R & P as the newer ones do. Plain old R & P is going to be harder to turn with.