In Stock items may be sold by Amazon or a third party. If it is sold by a third party there will also be a statement "Sold by seller's name and Fulfilled by Amazon" which I take to mean Amazon is acting as an agency for the seller.
"Fulfilled by Amazon" means that the actual seller stores its inventory at an Amazon location rather than one of its own, and Amazon fulfills orders. There are also listed products that are shipped by their actual sellers other than Amazon, same as with eBay.
With Fulfillment by Amazon (FBA), you store your products in Amazon's fulfillment centers, and we pick, pack, ship, and provide customer service for these products.
Amazon also offers fulfillment service to sellers on other platforms, which is why some items purchased on eBay come in Amazon packaging.
If a product is ordered through Amazon it is backed with Amazon's return policy which I have also found to be easy and fast. When I have returned an item to their drop box the refund was deposited to my credit card account within 24 hours of my placing the item in the drop box. That includes items that were not satisfactory for any reason.
Not all items offered on Amazon are backed by their return policy, and I've seen items change from one status to the other as their prices changed.
Also, I've encountered something odious in their return policy: I ordered and returned three different brands of compression elbow brace, all of which sported a
Return this item for free
Free returns are available for the shipping address you chose. You can return the item for any reason in new and unused condition and get a full refund: no shipping charges
banner, but when it came time to return them because of a bad fit, the only free options I was offered were drop-off at either a Target or UPS store.I had to waste my time calling Amazon to get the promised "free" shipping label.
That's sneaky, underhanded, and altogether NOT cricket!
(In the instances in which I was returning one size to get a different size I got around the roadblock by saying that the second item sent was the wrong size and returned the first, and since my reason for the return was Amazon error, the free label came up automatically.)
Your prompt refunds may result from your being a Prime member; when I use my daughter's Prime account I get my refunds when I drop my return packages, but when I use my own account I don't get them until UPS says they've been delivered.