I want to say there is a big difference between 13 and 14 for kids because there was for my kid. But, I know it depends on the kid. We know one who looked like a man at 12 - and then changed little over the next 2 years. And, we know another who seemed stuck at 13 and 14 and then shot past many at 15. Puberty is not the same in terms of timing for every teenager.