Dealing with roommates
In high school you get to go home to your comfortable bedroom where you are used to everything being how you like it. In college you might end up getting forced to live with someone that you don’t like very much. Welcome to life in the dorms, where roommates are required and you don’t get to choose who you get.
You have to actually learn
Maybe you liked learning in high school but our goal was always just to memorize the text and pass the tests. In college your focus is on actually learning. You will be using these skills immediately after you graduate in order to pursue your chosen career.