I think many of the differences are due to the Cows being photgraphed at different angles. The black one is shot straight on, the brown one is tilted slightly.
Stitching is never going to be exactly the same between two items even if they're the same style. From the style number, the original was made in or around late 2010, and the newer ones listed on Ebay with the F Factory Store codes probably made no earlier than the last 12 or 18 months. Not only will there be small changes in cutting and assembly details, but I've noticed even the
Coach stamps and hangtags aren't made quite as precisely as they used to be 4 or 5 years ago.
Something else to consider - if the brown one is fake, where are the rest of the brown fakes? No fakes maker is going to make just a tiny handful (or just a one-off!) of a keyfob that is exactly like the original including a lot of time-consuming details - where's the profit in that?
(I actually like the brown one. The Black and white one appeals to me as a Midwestern girl because I love seeing hundreds of those beautiful black and white Holsteins on my drives around Wisconsin, but the brown one has a more European look - Guernsey, maybe? The brown fur color reminds me of Highland cattle which I think are gorgeous. And forgive me if I get the names wrong, I'm a City Girl!)