LOL. When I was 15 there were two boys in my class. One was 2 meter tall and the other was around 160 cm tall (the poor guy only attracted 11-12 yo girls and he hated each and everyone of them). They didn't have that big a body size difference as they do in that picture.
This is supposed to be a 16 yr old next to a 17 yr old? http://www.mangago.zone/read-manga/ossu_ren_ai_gakuen/mf/v01/c002/23/