China's success has come _after_ they economically liberalized in a way that resembles the west's free markets.
Soviets never did any of this. They "stubbornly" kept to a command economy. While china does have their 5-year plans and command economy, they have loosened that up for private individual's enterprises, and allowed special economic zones for which free market capitalism thrives.
With a bit of state help in infrastructure etc, this enabled china to leverage their enormous human capital to simply out-muscle their way into industrial dominance. Now with such a dominant position, they can call shots in a way that irks the US. Compounding the problem is that the authoritarian style of gov't in china enables long term strategic planning and execution - something that seems sorely lacking from the US for the past 3 decades.
Why does the added qualifier in your first paragraph matter?
You’re literally just explaining why the Soviet Union was less successful.
Nothing stopped the Soviet Union from liberalizing their economy and running it better like China. They just didn’t do it. Which loops us back to my original comment.
I didn’t bring my point up as some kind of communism versus capitalism thing, I’m just plainly stating that as far as single-party mostly-authoritarian governments go, China is far more accomplished than the USSR was.