This thread reminds me of the time, several years ago, I got into watching part of a season of “American Idol,” only the first four or five episodes to see how awful the singers were, and then the final four or five episodes to see the good ones. I never watched it before that and I haven’t watched it since.
The show was holding auditions in some major city in the American heartland, I think. The judges were Simon Cowell, Randy Jackson, and Paula Abdul.
One contestant got his golden ticket (all three judges moved him to the next round) and ran out of the room, to be greeted by about a dozen family members and friends in the hallway, who the judges could hear yelling in excitement through the closed door. Everybody was hugging and jumping up and down. Simon turned to Randy and Paula and said something like, “You Americans get so excited when someone you love does well.”
Randy and Paula stared at him and Paula said (again, paraphrasing), “Well, yeah, sure. Aren’t you happy for your relatives when things go well?”
Simon said something like, “Well, I suppose so, but I don’t get THAT excited.”
So definitely, one major difference is demonstration of emotion, from what I’ve read in these posts. The British are more reserved in this regard, while Americans aren’t shy.