People in the US are more racist, while people in Europe are more nationalistic. It is a fact that will probably never change. For example, it wouldn't be at all strange for a Pole to prefer a Nigerian to a Russian, or for a Kosovar to prefer a Chinese to a Serb. Europe is a mosaic of nations with complicated histories that make the question "what nation are you from?" more important than "what is the color of your skin?". In the American "melting pot", skin is the only thing that doesn't melt, so it's a strong basis for racism. A concrete example from a few years ago: my father, a European, traveled by plane from Washington DC to Seattle. Checking for any terrorists, the police at the airport routinely separated the passengers into two groups: one included only white people (Americans and Europeans, my father included), the other included people with darker skin (not just Arabs, but also Latin Americans!).