eBay has an auction-style option for selling items, whereas Amazon does not. This makes eBay a more suitable choice for buyers looking for used items, preferably cheap, and sometimes rare. Depending on what you’re selling, item condition might not be the top priority for eBay shoppers.

There is a huge opportunity for your business reseller, you can buy cheap stuff from amazon (discount), then sell higher on Ebay.

No they are not, in fact they are competitors.

Is the Pope affiliated with the Reverend Sun Young Moon?

No. They are totally separate.