One of the things I have noticed, primarily watching Premier league games, is how rarely fouls are called when two players go up to challenge for a ball in the air. The particular circumstances are when two players go up and one gets to the ball slightly before the opponent so wins the header and the second player hits head to head with the first. Typically when this happens the players both go down holding their heads and play is stopped for the injury. It is almost never called a foul on the player who didn't win the challenge. Is there anything specific in the laws that makes heading the ball different than kicking it for this purpose? I have never found it but the way it is called seems quite different.