Silver is really long and lanky & you can wrestle this headcanon from my cold dead hands, whereas the other 3 are mostly the same- Shadow’s heels make him look taller than he actually is though (also this Amy is about 15 because a younger Amy would be noticeably shorter)
Other stuff: Silver has pink eyes because I love albino Silver, Shadow has the piercings because he had an ear tag on when he was younger and living as an experiment on the ARK and the hole never healed so he uses it for piercings, and Amy has her Fleetway spines because they're better fight me