Whats the diference between Mobil One GM4781M and GM4718M I see at Sams Club?

Was this seen on the product or a piece of paper at Sams club? I'm wondering whether it was a mis print?

Was it labeled that way on the bottle or the print?

It's just going to be the weight of the oil! Just look for the wieght and if it is synthetic or a synthetic blend and put it in your car.