That is really a weird blanket statement: Both places have their own weirdness.
You probably aren't going to do so well with a start-up in rural Mississippi or Indiana, mostly because folks don't have much money to spend on your wares, yet in some other areas it'll seem like they are doing well. Same thing with Europe. There are a lot of countries and economies and different regulations there and it is quite hard to compare with the overall thing.
(I think we should measure virtue by carbon footprint/chance of horrible death/crime/etc and not by GDP.)