The W mint mark coins are minted on different planchets than the bullion coins. They are a step above the panchets used for bullion and, if you will, two steps below the planchets used for proofs. Both uncirculated and proof coins use higher stamping forces than the bullion coins and proofs are struck twice. Far fewer coins are minted from each die pair for both uncirculated and proof coins as compared to bullion coins. Only the bullion coins are bullion coins. Just because a coin is minted in a precious metal does not make it bullion. The uncirculated and proof coins are both numismatic products that are specially minted, and individually handled and packaged for sale to collectors. Yes, they are basically the same design and composition as the bullion SAE but they cost more to make than the bullion coins can be bought for from dealers. They are never allowed to touch each other during production, unlike their bullion counterparts which are packed 20 to a tube, 25 tubes to a box for bulk sale.