Amazon: QN82Q6FNAFXZA

Costco: QN82Q65FNBXZA

Amazon one says Q6F, Costco one is Q65F. Not sure what the difference is. Aside from any spec differences (if any exist) you'd just be considering the value of buying it from Costco - 90 day return, second year warranty, Concierge support. Costco one also comes with SquareTrade for free, which would be $192 on Amazon. Up to you I guess if that adds up to $500.

Also I'm seeing that Amazon only has one available at that price from that specific seller. As soon as that one unit is gone it goes right back up to match the Costco price.