I wouldn't say college is much harder than being a high school senior. In terms of academics, this can obviously vary greatly depending on your high school, your university, and your chosen major.
High school basically eats into 6 hours of every day, 9-3 roughly, maybe a little longer. At university you will probably start out with 15 hours of class a week, but could be anywhere from 12 - 18 (doubt you'd do more than 18 as a serious athlete). So your basically cutting your in-class time in half.
If you live on campus, this is another easier slice of life than living at home. First of all, you save tons of travel time (obviously to compare this depends on how close you are to your high school and how close you live to your classes in uni).
While living on campus provides a great many distractions, I find most of these are more manageable than at home.
The adjustment also depends on how independent you are already. IF you need your mom to tell you to do homework and do your laundry for you, then those are things you'll need to adjust to. Likewise, if you're used to cooking for yourself already, you will either be more prepared to cook for yourself at school, or will appreciate the luxury of a meal plan and the extra time in your day that it affords you.
With homework, there isn't as much day-to-day or week-to-week stuff in terms of marked items, but there are a lot of readings and so forth, of which you'll realistically probably only read around 50% of. Mid-term time and finals are definitely more stressful than high school, but not unmanageable.
Every semester or few months you'll have to barrel down and cut through a lot of paperwork like you are right now, but this application process is probably the worst of it. You'll have battles ahead of you and stupid administration to deal with at some point in the future, I promise. But post-secondary is where it's at bro.