Likely the chronological age, mainly because it would explain the differences in puberty stages between the two boys, which is an example of physical maturation.
How to stop all together. But you should also see a counselor or get professional help, because you can't just up and decide I'm not gonna drink anymore, it is hard. The professional help will guide you, and give you substitutes, and help you through your problems.
If you meant drug instead of drive the answer is a wetstick