Another difference between Finnish and American schools that make it difficult for both easy 1:1 comparisons and reproducing Finnish results is the fact that the US, unlike Finland, is not a homogeneous culture (BTW, I know there are Swede-speaking Finnish citizens, but that's an ethnolinguistic difference and not quite the same thing).

So making such comparisons isn't quite so simple. This has been discussed endlessly in previous HN threads. I encourage you to search for them and read them; there's some interesting discussion there about this, so I won't rehash it here.