They actually tended to get the same hairstyle when they went in to see the barber. Harry had found, once he had the freedom to choose his own hairstyle, that he could tame the Potter locks by either wearing it long to weigh it down, or short so that it didn’t get the opportunity to be all over the place. After trying both ways, he decided that shorter looked best. Tony liked to keep his short hair neat and would keep pushing the front of his hair back, to wear under his work caps, while Harry would let his fall forward over his forehead. Harry didn’t really mind his scar any more, since the final battle with Voldemort it had faded and now, unless you knew it was there, it was really hard to see. The hair over his forehead just helped the faint lightning bolt line disappear even more.