How do A levels compare with US High school qualifications?

Are A levels of a higher level? But then in the US you take more classes. And what about AP classes?

Before I start, I just want to say I've lived in the US my whole life so I know about APs/SATs/SATIIs/ACTs, but I don't know very much about A levels (I'm going to the University of Edinburgh in the fall so I think I learned a little about A levels through the whole application process, but I'm not sure how right my assumptions are).

It's hard to compare because A levels cover more of a given subject whereas APs are more specific. For example, in terms of the subject of history, I believe the A level would be 'History'. But for APs, you would take 'AP European History' and/or 'AP World History' and/or 'AP US History'. Same with math, I believe the A level would be 'Maths' and the AP would be 'AP Calculus AB' and/or 'AP Calculus BC' and/or 'AP Statistics'. I think the difference comes from how you learn them. I'm not sure if you do A levels only in your last year of high school or in the last two, but either way I think you only pick a few of them. 3? 4? In the case of APs, you pick as many as you can handle (for some people that's one AP class and the rest of their classes regular, for others that's every class is AP). I think most high schools in the US have 6-8 different class periods available, so I know people who are taking 6 APs at a time. (I only ever took 2 at a time, I think 6 is a little extreme, especially considering you start taking APs in sophomore year. I did 2 each year, to graduate with a total of 6.)

In terms of the class itself, APs are generally just regarded as being harder classes. They take up more time in terms of homework load and require a lot more effort. In terms of college acceptance, APs definitely count and are one of three categories of standardized testing that is looked at in addition to grades/GPA and personal statements/supplements. In these three categories, you take: 1) APs or IBs, 2) the SAT or ACT, 3) SATIIs. APs are the standard in group 1, but there are some schools that only offer IBs so the students there have to take them instead. In group 2, the SAT used to be the standard but now they're pretty much even. Group 3 is the sort of optional group: you really only take SATIIs if you've done the AP in the same subject, they're good to have but not essential, and colleges usually only ask for two or three.

I hope I answered your questions, if not just let me know and I'll try to be clearer, I feel like I kind of rambled on, sorry!