Really very different from what you are use to. But under it all, teens are very similar around the world.
All freshman are a bit clueless, so good grade to go into. All freshman will be trying to find their way.
There is a lot of other activities. Many students are involved in something. Band, choir, orchestra theater. There will be all kinds of sports teams. Going to sports game is popular to do. There will be different coins and organization to join.
HS can vary greatly across the USA. Some are very large , some are small. Some have many different facility, some don’t have many at all. Some are excellent academically and some are not.