Growing up is a function of your life experiences.

If you go to a basic college, read basic things, watch basic shows, and have basic friends, then your life will be basic.

Leveling up is a function of the goals you set for yourself, and then the degree to which you pursue them.

Sometimes, leveling presents as similiarity. For example, classical piano players seem similar, because they have leveled up their brains through repeated exposure to similar stimuli.

Still, to grow up is to be passively shaped by what life gives you.

And to level up is to actively choose what shapes you, in order to experience something different than what would happen by default.

Perhaps this is what is meant by the renaissance ideal. What sort of person do you become with an athlete’s body, a scientist’s mind, and an artists soul? Perhaps a genius, in spirit.