If the Chinese restaurant you are sitting in does not have a separate menu for Chinese-reading patrons, it’s not a very good Chinese restaurant. However, you are getting the same food, with at most some minor differences in presentation and seasoning. Of course, a long & complicated request for some special treatment will be more likely to be understood if made in Chinese. There might be specialty dishes not on the English menu; but then, there might be specialty dishes not on the Chinese menu too.
I can’t account for the difference in pricing, and neither can my resident Chinese-culture consultant. Indeed, the latter suggests that it would be better economics to charge Chinese customers more for the dishes, since they are, on the whole, lousy tippers.