The main thing is that you got hired to work a college game and a high school official might not.
The main thing is that college officials tend to think in very specific issues when it comes to officiating plays rather than just blowing the whistle to call a foul. They tend to know why they are calling a foul and why they should not call a foul. Part of that is the exposure to camps and having been evaluated on many plays down to the minute it took place in the game. But there are always exceptions, just some things I have noticed.
Peace