I have one little anecdote that sums up the difference I have found between people in Britain and the USA (excluding people in the bigger cities like New York).
I lived on the Gulf coast for a while and one day whilst walking on a pier by the beach I saw a lady with a pram (baby buggy) with people smiling as they walked by. As we went by I looked down and saw in the buggy, not a baby, but a duck. A full grown fat feathery mallard chunnering up at everyone who passed and spoke to it and its pusher. And everyone, of whatever age, was friendly, smiling, chatting to the lady like it was the totally charming thing that it actually was. I thought about back home and pondered that if the lady had done the same thing where I came from she would have found herself hounded and taunted by a pack of sniggering, laughing, rude, abusive, teenagers, and probably a few adults too.
Generally speaking; UK==rude; USA==friendly. YMMV.