Perspective.

Your current environment and the current problems you face help to shape your perspective on the world. It matters when you're talking about someone who is currently in high school vs someone who has been out of school for a while and working in the world.

Most of the time, it changes with age. It doesn't mean you get more mature or get better at thinking a certain way, it just means you have a different way of viewing the world. It's complimentary to how you apply critical thinking and how you make decisions. If you're in high school, the problems that are the biggest deal to you are probably just not that important in the grand scheme of things. But because you lack perspective and because you are immersed in them, at that moment they are the biggest deal in the world. Your first relationship, your first break up, your first job. No one is perfect and it takes time to fail at some of these things and learn from your mistakes. You can be intelligent and young but unless you have experienced these failures, you're not going to have all the answers. So yeah, age sometimes does grant you some additional wisdom.