Hi,
It's a very interesting issue. I have come across with a few Americans outside of America.
My experience is that in general Americans are more self-centered. If I ask them where they are from, they normally don't say they are from America, they always said LA, California, New York or Florida, etc... Their replies make me feel that they think "America" is the center of the world and that's why they use "states" or "cities" as their answers. Be aware, I asked them before I knew they were Americans and I asked the question when I was in NZ, Australia, Europe and other countries outsite of America.
Cheers
Barry