Questions about twins body differences?

On a genetic level, you are both the same since you came from the same zygote/egg. That doesn't mean that everything will be expressed exactly the same even though you are "identical", you don't have to be the exact same in every way. From the moment the cells divide, there can be some random changes that put you on your own path. Only at the moment the egg divides were you exactly the same. That would account for many differences that you mentioned. Hair and the pattern of maturing included. It's not unusual for brothers to share things with each other, particularly when they're twins. You're the same in so many ways, I can easily see how you would share this with each other as well. Hope that helps.