Amazon is now for the “we technically have QA but honestly don’t give a shit” sellers. Not quite alibaba but getting there.
The core distinction between Ebay and Amazon is that on Ebay each shop+product combination is its own listing and the seller reputation is put up front, with the buy button below the seller information. Meanwhile on Amazon there are product listings, with multiple sellers providing the same product and the seller name being put below the buy button. There is no obvious indication that you are buying from a third party seller on Amazon, whereas on Ebay you can only buy from third parties, so expectations adjust accordingly.
Makes for using independent store fronts a breeze because almost every checkout experience through shopify shares a common login and CC info.