Since I am getting older and like explanations simple and straight forward.... Here is my take...
An auction is a "competition"... Whether it is on the 'net, in a "brick-front store", in an open arena or someone's backyard... I have to compete against others to be the "High and/or Winning Bidder"... As such I win an auction...
When I go to the Grocery Store, Furniture Store, Home Improvement Store...etc.... and I purchase and item.
I, myself, consider it buying an item...
Unlike at an auction, retail facilities have countless numbers of the same item(s)... In fact it is common to find dozens, hundreds, thousands of similar items next to one another on the shelves.... Very rarely, is there just one of an item... If an item is out of stock, it can be brought in from the Warehouse, another store, from the Manufacturer.... etc...
Unless it is a fantasy or repop... it is extremely rare for there to be more than one of an item at an auction...
But, that is just my take on the difference between "winning and buying".....
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Looking for Tide Water/ Tide Water-Associated/ Tidewater items