For the most part that's true but any tiny difference is used against a group if it fits in some other group's argument. It's funny how Asian, Hispanic and African descendant people in the US are singled out while all the Irish, Italian and Jewish are only viewed separately on second inspection. I mean, if it's all white-looking people in a place, they differentiate Italians, Jews, Irish, etc., but before that it's the skin color (on level 1). I suppose this is some natural reaction homo sapiens has had for millions of years and not necessarily ill-meaning discrimination. Some anthropologist with more insight here?