AP classes aren't really close to college classes; main difference between AP and normal course being AP you just get more work and learn more shit during the course. They are definitely pretty damn challenging, though, no doubt about it.
Actually it is like a college class. Here's a quote from wikipedia.
The Advanced Placement (AP) program is a curriculum in the United States and Canada sponsored by the College Board which offers standardized courses to high school students that are generally recognized to be equivalent to undergraduate courses in college.