There are a few key differences between Sphynx and Peterbald cats. For one, Sphynx cats are known for being almost entirely hairless, while Peterbalds can have varying degrees of hair loss. Additionally, Sphynxs tend to be larger than Peterbalds, with both breeds typically weighing in at around 10 pounds. Finally, the two breeds have different temperaments; Sphynx cats are generally more active and outgoing, while Peterbalds tend to be more laid-back and calm.