American Schools Considered Bad Compared to European Schools?

I was wondering what AP classes and schools were like in Europe that makes it different from the schools in America. I go to an International Baccalaureate school- or IB for short-, which means that all of my classes are considered AP (Advanced Placement) or honors in America. A lot of the time it is difficult, but I pull through just fine in the end. So, every body's other outside friends go to other schools that are NOT IB- or in other words plain public schools (not specialized), but may have honors or AP. Being kids, school is something that every kid in the U.S. has in common. This makes it a main topic of conversation for many kids and teenagers. My sister's friend is in honors at a school in my neighborhood. He has a friend that came from Europe, who is also in honors, who said that school in America is a joke. That it is so easy, simple, and basic that he had already learned all of the things that he's learning in high school his entire life. He had been taking basic Chemistry since kindergarten. Our AP Chemistry in America is equvalent to 8th grade Chemistry in Europe. He also breezed passed AP Calculus, because he had been learning basic caluculus since 6th grade. After getting this information, I'm not sure if American schools are really that far behind other countries, such as countries in Europe, or the schooling in Europe is way beyond the average learning curriculum. Do we look dumb to them? Because it seems as if some other countries look down on us in terms of education. How come we don't  have the same requirements? If we were to go to school in America our whole lives and then go to learn in a program in Europe, would be that far behind?