First of all, there is no way to conduct VS, that is, direct PK. Judging from the weight and fighting, a strong man will win.
Secondly, in terms of flexibility, young and flexible boxers are physical advantages, but the strong men in the gym practice this, and their physical coordination will not be weak. In this respect, both have their own advantages.
Thirdly, in terms of explosive power, early adolescence is dominant, and with the passage of time, explosive power weakens. Fitness strongman pursues persistence.
Finally, from the perspective of human nature, the strong should lose with a slight disadvantage, because the future is a teenager, and he doesn't want to dampen his enthusiasm.