One of my neighbors is a diplomat for the Russian Embassy, and we talk a lot (he likes that it lets him practice English, and I like to hear his perspective on things; not to mention he tells incredibly interesting stories about commanding Russian destroyers).

He told me once that the biggest difference he saw so far between Russians and American's is that if you ask an average Russian if they can do something, they'll say something like "Probably not, but I'll do my best.", whereas if you ask an average American, they'll say "Absolutely, I'm great at this." irrespective of their actual abilities.

That's a pretty broad generalization, but I think there's definitely a cultural difference between a more cynical Russian culture and a more optimistic American one.