It may be school dependent, but at ours there absolutely is a difference. The top level classes are full of super smart overachievers so they move very fast and the level of work expected is extremely high. Our kid somehow managed to test into one of these classes. It was struggle from the get go, in spite of ton of work, going to all office hours and a ton of studying he could never get above B level. And it was sucking up way too much of his time. When suggestion was made by the teacher to move down a level (which is still accelerated class just not the top level) he was not happy to hear it but reluctantly did it. What a difference! He managed to get As on pretty much every test with just doing homework, no need to chase office hours or do hours of review for every test. The fact that he was near the top of class curve instead of the bottom made huge difference to the amount of work required to succeed. I know several friends had the same experience. So the correct class placement is a big factor here. But even without that, some classes are known to be killer in terms of work required, there are several STEM classes that are famous for it. True college level work. This is not the case for the regular or even the accelerated classes, which are advanced high school level. And there is level of difficulty, but also how time consuming the class is, huge variation among electives in terms of how much out of class time you have to spend to complete projects, practice etc.