Ok, some differences between the college and high school exams are probably the stakes are higher and the rate at which you take them: how many a week and how long you have for each. Now what is harder or easier, probably depends on the subjects. using curtain tools or ways to do a problem you learn in college could make it easier than what you had in high school. Unless of course it's the same confusing messed up junk that you already "learned". Preparation, well, that's easy. take the notes, study, do what you normally do.