The difference is that laws in China require companies doing business in China provide the Chinese government with means to access all data crossing Chinese borders or involving persons of interest. You can read the DSL of China yourself; and consider that nearly every executive of any significant Chinese company also holds an office of some sort in the Chinese government, there are a vast number of Chinese nationals who are considered "persons of interest" to the national security of China and therefore fall under the DSL purview.

Any company building or selling software in China has to provide the Chinese government with access to data collected in China, or outside of China if it involves persons of interest for national security. Like I said, find the DSL and read it yourself, or read an InfoSec analysis of it from a company you trust - you don't have to take my word for it.

This immediately puts Chinese software into a different category of risk than non-Chinese software. Of course, the US could twist arms to get companies to put backdoors in software. But it's a false equivalency to say that they're the same. When the US does it, they have to do it covertly, and there's always the risk of a leak. When Chinese companies do it, they're doing it because Chinese data laws require them to.