The only difference I saw was Sparky's are square and OEM are rounded. Would love to have the machine that cut them round like that lol I would give it to Sparky for a set of labels pre cut of course :-)
If you really want one, look for a rounded corner punch in the scrapbooking section of craft stores (like Hobby Lobby). They come in many different radii so surely you can find a match, and they're luckily pretty cheap (~$5).
Sparky was dismissive when I brought 'em up, and I have to agree after using a few stickers; the curve ain't worth the effort to me and the stickers look great as is, but to each their own.