Studies have proven that adults have a more developed brain than teenagers do, they have a larger prefrontal cortex which helps them make wiser decisions. by now proliferation is is still growing but not as much .
The teenage brain is very different to the adult brain as the brain is changing and growing everyday from the back to the front. Teens tend to make worse decisions and take more risks. Teenagers are very responsive to rewards the stirdum lights up.
Teens make decisions based more on the emotional side of the brain than the rational. It also depends on what the reward/who is there that can influence a teens decision. The amygdala is responsible for immediate reactions including fear and aggressive behaviour. The amygdala develops early, whilst the frontal cortex develops later (the part of the brain that controls reasoning and helps us think before we act).
Adults tend to be more wise in there decision making, as there amygdala isn't what they make there choices with. They have had more life experience than teens so they can tend to make better decisions, there brains also don't get as excited for rewards as teenagers do so the reward doesn't matter as much. most of the decisions are made in the frontal lobe. (Thinking, Reasoning and planning)