If the part number is the very same at Walmart and at the small A/V shop, the tv is the same. If the Walmart p/n is different, even by one character, such as adding an A at the end, you can be assured that the Walmart tv has been built specifically for Walmart. The manufacturer has caved to the extreme pressure that Walmart applies, and made a special model for Walmart. The Walmart model will be cheaper is some way.
Imagine sitting across from a Walmart buyer at their corporate headquarters. The buyer insists you give them better pricing. You say no, we've already done all we can. Walmart says fine. Our contract is done. We will no longer carry your product. You realize that Walmart represents 20% of your sales. If they don't sell your product, you won't pick up that 20% elsewhere. So you cave. You agree to build a special model just for Walmart. It will look just like the model sold elsewhere, and have almost the same p/n. But it will be different inside. Something you can do cheaper. So you do it, to keep that 20% of the market share.
Don't think it happens? Then you are living in a fantasy world. Shop a dozen items at other stores. Items from small appliances and electronics, housewares. Then find those same items at Walmart. I'd be willing to bet that more often than not, the Walmart item will be a variation of the item you found elsewhere.
