well food from one nation is going to adapt when it is transplanted to a different nation due to available food supplies and prices. obviously whats common in stores there is different than stores abroad. Also, Chinese food in china is very regional so if you go to different regions it may be very similar or different from what you get abroad. Also Chinese food abroad has adapted somewhat to the preferences of the people in that country, they are trying to run a business after all.
i personally didn't feel that most of the food in china was significantly different than what i could get in the states.