If the NAME on the Michelin tire is different at Costco than on the michelin website, then the tire really is different.
Goodyear does it, but I don’t know about Michelin’s policy of building different tires to meet the price demands of the retailer. ie; Goodyear does it for Walmart. You can NOT go to a Goodyear store/shop and buy a Goodyear ‘viva’ tire. It truly is a different, CHEAPER built, cheaper tire, hence it’s different name.
The clue to look for at costco and all the other big retailers, whichever brand you consider, will be the NAME of the TIRE, not just the brand name.