The transition from high school to college can be different to say the least. When students make this transition they tend to notice these things the most:
1. The difference between classes.
Most professors don't tend to take attendance because they don't care if you are there or not. In college you will have a couple professors who are strict about the attendance policy, but the rest will only care if you show up to every class. In high school if you missed so many classes you could get in trouble, but that is not the case in college.
2. The difference between living conditions.
In college you are not at home in your own bed, you are living in a dorm room with a total stranger. There are going to be roommate problems and arguments. There will be times when you wish you were still living at home with your crazy family.
3. The difference between course work.
In high school, you could probably get away with missing a day of school and still understanding what was going on in the class. Well that isn't the case in college. If you miss one day, you will be behind and you probably will need to go to office hours and get help.
4. The difference in eating habits.
At home you may eat healthy home cooked meals, but in college nobody's got time for that! We either eat the caf food (which tends to not be so healthy) or we eat ramen in our room on a daily basis.
5. The difference in how much you miss your family!
In high school all you want to do is get away from your family, but in college if you are like me, all you want is to be home with your family. I go home on a regular basis. I am a homebody, and when I can't go home, I call my family five to ten times a day.