sku's, upc's, barcodes, and barcode scanners

[BillV]

Our company makes and sells handmade soaps, lotions, and other bath and body products. I had a prospective retailer (a grocery store) ask if I had a upc. How are upc, sku and barcodes different. The reason is I want to be able to provide this on our products for retail wholesale. If I create a sku on my items, will another retailer like the grocery store be able to use the barcodes i create from them or are they unique to my square store and POS. Do I need a 3rd party to create a upc, or sku, or barcode (not sure which is appropriate for my situation)? I also want to incorporate a scanner into my POS at art shows and mall kiosk drop ins. The next part of my question is this. Is there a barcode scanner that works with an android phone like my galaxy note 20. It would make checkout much faster when I am busy. 

[rtfulk]

If i'm not mistaken, I think you will need to purchase SKU's to sell to retailers. The reason being when you purchase SKU's they are assigned to your product, that way it won't be a duplicate for another item the retailer may be selling. We don't sell to other retailers, so our sku's are generated in the app and don't need to be purchased since we are the only one's using them.

You can do a search on google for purchasing sku's and there will be several companies you can buy them from.