Certain elements of the U.S. version will remain, including appearances from well-known Chinese actor Wang Xueqi, as well as footage shot in Beijing last December; though the Chinese version will include extra footage shot specifically for its release, as well as an appearance from actress Fan Bingbing.
The Chinese government keeps a tight lock on the number of foreign films it allows to screen in the country each year, while its censors are similarly strict over the content of those movies. Many foreign films will file for Chinese co-production as a way to hedge their chances, but Marvel and DMG decided against that route, choosing instead to cater the final installment of the Robert Downey Jr.-starring trilogy to the domestic audience.
Such moves are necessary as China's film market has grown significantly in recent years, and many expect it to rival the U.S. in terms of box office numbers within the next 10 years.
Iron Man 3 opens in the U.S. on May 3rd, while the Chinese release date will be announced soon.