The difference is in the stocks and finishes if any at all. Walmart will make a very large order direct to the manufacturer, they have no middle man, and usually it will be an economy gun, matte metal work, cheap plastic stock. Using the Rem 700 as an example, I can buy one at Walmart for $300 with sights, $325 without. That of course makes no sense to me as the sights will set you back at least $25 if you tried to buy them.
That is much less than wholesale.