The big difference is religion.
Italy notwithstanding, Europe seems to place far less emphasis on religion than does the US. I've had interactions with many music industry people in Europe, and not once has religion come up. The last time I flew to Nashville, the record exec sitting next to me on the plane asked -- within a few minutes of meeting -- what church I belonged to.
Without religion to dictate what's right and what's not, people become much more accepting.
One of my most enjoyable nights in Europe was at a club in Ibiza called Space. What I loved about it was that the crowd included all types: straight, gay, male, female, young, old, pretty, not so much. And everyone accepted everyone else. Just as I would be telling a young women how hot I thought she looked, her boyfriend would be telling me how much he admired my body. Very cool.
I can't imagine a party like that happening in the US. A shame.