High school teachers always say, "This is how things will be in college. I'm trying to prepare you for those days ahead." From a college sophomore to you, a high school will NOT prepare you for college. How is that so? Well...
In high school you write in MLA format with little to no deviation from it. In college, be prepared to toss MLA away and never use it again. Start familiarizing yourself with APA and Turabian formatting now if you hope to be prepared for those vigorous collegiate essays.
In high school, math teachers tell you that calculators won't be available in college math classes. Unless you're in a major that is heavily math or science oriented, you will likely only have to take one math class. This math class will likely be basic and a calculator will be allowed for every assignment. Don't let your teachers scare you.
In high school, homework on the weekends is a rarity. Unfortunately, in college your weekends will probably be dedicated to finishing the abundant load of homework you've been assigned.
Many high school teachers give you an idea of what to study before a test or will tell you the test format. In college, study everything and hope for minimal short answer questions because until you get the test, you're going to be completely in the dark about the test's content.
In high school there's a strict attendance policy. When you get to college, attendance may be part of your grade but aside from those few classes, it's up to you to show up every class. Go to the class because if you get behind, it's nearly impossible to catch up.
High school has a social order that doesn't continue in college. There won't be any "populars" or "geeks." If you take your work seriously, you're going to find yourself being respected by your peers even if that wasn't what you experienced in the past. Likewise, if you're the social elite in high school, college isn't your kingdom to rule. Take school seriously and find those multitudes of people who share your interests and beliefs. College is the time to find those true friendships.
High school gives you classes out of obligations to state requirements. College will give you some general requisites to take, but for the most part you will find yourself in courses that interest you and prepare you for your future career. It will be the best change you could possibly experience because at last you'll be studying your passions.
High school won't prepare you for college. You'll have to adjust to the new setting and expectations which will be tough, but it will be worth it.