I honestly don't think there is a different of the toy's quality or packaging because as far as I know, Bandai does not manufacture different packages or shells for different stores in the United States. I've looked at Tamagotchi both at Walmart and Toys'R'Us and the items at both stores were in good condition.
Very true :mimitchi: I know that Bandai will make Tamagotchi for certain corporations every once in a while (such as for Japan Airlines) but I think even then, Bandai tries to strive for quality.
Bandai manufactures the same item, they just ship it out to differnt places. All stores you buy them at carry the same Tamagotchi. Some stores, like Walmart, tend to get them faster where I live for some reason.