When the big boxes get a product that is not the same as your supplier (or even the exact same one with a cheaper retail price) they will put a different model number on it.
That makes the bookkeeping easier and it gives them an out when the guy pays more at his supply house.
Your supply house will seldom be able to match the price of a big box on identical products. The big box has less overhead per unit and the big box offers a lower level of service.
