OK I'll bite as the parent of one definitely, one waiting diagnosis other but 99.9% experts sure they also are teens.
My elder teen is 16. Younger one is 15.
Younger one with confirmed ND is often shy, can be mistaken for withdrawn. As a result with Covid cutting in person lessons, teachers didn't pick up on how bright he is. He was pigeonholed as mostly near bottom group for attainment.
In fact, he was bored. Found the work tedious. Would not speak up as he didn't trust the staff yet. Wouldn't let me either.
Once he got to know the staff, especially his tutor, he has excelled. He has a close group of 6 friends who all have gaming in common but who have also made him dip his toe into a love of football. He can be himself with his, some would say interesting, sense of humour. He becomes hyperfixated on something every few years (unlike the other one whose fixations change almost monthly, more if stressed). It's currently flags.
Staff now know to check in every so often, because he won't always moan.
So yes, around trusted people, friends, family, family friends, teachers, he is happy to chat and comes across as a normal, if not somewhat nerdy, teen. Around new people? We go back to withdrawn, quiet, shy teen who is unsure of himself and their viewpoint of him.
The worst point was the time in late August 2020 when school announced it was reopening post lockdown, and there would be different timings and a one way system, along with zones for break time for each year group.
This resulted in a huge meltdown in the car. He couldn't sit where his friends sat every day prior to lockdown. Would they find each other? Would he get detention if the one way system made him late to a class? What if he had new staff?
Literally he was inconsolable to the point of making himself vomit. It was some what helped by a staff member who asked him to pop up to school the day before it reopened so she could show him where everything was, give him his timetable and a card that allowed him to have 5 minutes grace to lesson. Even his mates, who are stars, text him and they arranged a designated meeting spot for break time. If those kids could understand how certain situations can effect a ND friend, how the hell can't a grown adult?
It's a juggling act. To suggest teens with ND won't do what all teens do and go out and be a bit naughty with drinking is ridiculous. The way you speak makes me think you're the type who thinks that people with illnesses or issues should be locked out of public view.