in simple words polish clears out wax and eats up the clear coat of your cars slowly and gradually..
wax creates a thin coat, fills and smooths the clear coat 
I hope I'm right 
I've applied wax a couple of time and the less you use the better.. trust me that works.. you just need to make sure the wax is applied on the surface.. if you apply too much spread it out.. thin wax coat really brings out the shine 