I'm a parent so take my advice with a grain of salt. But I'm pretty sure that college hasn't changed that much since I graduated.

One, professors no longer treat you like children. In high school, if you're tardy to class or you're late on an assignment, then a teacher will go after you to make sure you are either punished or your behavior is corrected. That's not the case in college. In college, professors no longer chase after you. They aren't going to make extra strides to ensure your success in academics. School becomes entirely up to you once you enter those college gates. You decide if you come to class. You decide if you want to turn in your homework. You decide on your education.

Second, the material is much more intense. I think you'll find that high school AP classes just touch on surface knowledge. College classes are a chance for you to dig deeper and learn more intensive material.

Third, college classes run at a much quicker pace. Don't expect to have things slow down to fit your pace. You will have so much more packed into your head over 10-15 weeks than ever before.

College professors don't wait up. Learn to move fast, take notes quickly, and dramatically improve your study skills. You'll need them for your midterms and finals that quickly creep up on you.

I relate better with professors who treat me like a peer, as opposed to just a student.