A common mistake on the backswing is to hinge instead of cock your wrists, a perfect drill to help fix this is to pre set your backswing by cocking your wrists right up in front of your face at address and then turning into a full backswing
There is a really small difference in stance widths, with your driver your shoulders should line up with the outside of your shoes while with your pitching wedge they should line up with the inside of your shoes
Maintaining the same posture throughout the swing is critical to hitting the ball in the center of the clubface