addendum on physics prep and GRE
Why? My understanding is that a US student will have 1-3 years of physics in high school (and that more than 1 year plus AP classes is unusual, and that this will typically be senior year at that); I would expect a European student going to university to major in physics to have had 4+ years of physics, and before that at least a couple of years of a lab based "general science" class. Now these are school physics - repetitive and basic; but that is how you learn, overlapping repetition building on what was learned previously.
As an example - when I started university, I had had 5 full years of physics (with chemistry in parallel for 5 years, and biology for 3 years]), in addition I had had 4 full years of a lab based general science - first lab class when I was 9, measuring and plotting conductivity and heat capacities - still remember it. In addition, since non-US universities typically have little or no Gen Ed requirements, and majors are usually strict structured in-sequence classes (though there is a deplorable tendency towards US style modularity recently, at the intro levels, modularity is great at the advanced levels); so each term a student will typically take more major-subject classes than a comparable US student (unless the US student overloads, or has the Gen Eds waived). European universities also tend to trimester systems (since Easter is a holiday, and sports are irrelevant), which makes for easier structuring of sub-topic classes, while the "big topic" classes are just taught as in-seqence (QM I, II, III etc;. E&M I, II, III; Mechanics I, II, II etc etc).
So a foreign student will spend more time doing physics, see more classes and cover more sub-fields.
Doesn't mean they're better researchers or more talented scientists; just more experienced in some way earlier. In fact some places complain the foreign students are too rigid, too indoctrinated and have lost the ability to think flexibly.
Just can't win...