My sense significant qualitative and quantitative differences.

If I recall correctly, and I don't have any sources, any business in China is technically owned by the CCP. A business might operate like it's free and private while it's small, but once it gets big enough, the state really does take it over. In the USA, the businesses are technically owned by the owners. The state might meddle using regulations or national security letters or things like that, but for the present the businesses are still owned and operated by their owners. If somebody has a source confirming or denying this I would appreciate it.

As for the totalitarianism, I think China is only worsted by North Korea, right? This difference with the USA is more about scope. The USA tracks, surveils, imprisons, assassinates, etc., but perhaps the latter two in a less broad manner. It's hard to tell because the USA officially denies doing a lot of that stuff. My sense is that everybody in China knows they operate under such a regime whereas in the USA the state denies it and people don't want to believe it happens here too.

If you look at the measures recommended in the Communist Manifesto's second chapter, it has been argued that most or all of them are present in the USA. So you're right that it's difficult to say "communist" applies to China but not the USA. We have to be more specific.