I agree that the “principle aspect” as you say, or which class is holding power and ultimately controls both the economy and the political system, is most important. I’d argue though that the primary difference in these sectors is who is in control of the surplus, and whose benefit it goes to. In the PRC and even in Cuba, there are still private capitalists who effectively control the surplus generated within those companies, and use it as they see fit. They’re severely limited of course, but they still function differently from the socialist sector whose surplus is worker-controlled via 5 year plans.
The only “socialist industry” I can think of in western countries, outside of tiny examples like coops, are things like state-run natural resource and energy companies. The US military is just the enforcement arm of capital, planned and controlled by capital. Even state-run social services shouldn’t really be thought of as socialist, since they produce no surplus value, and are funded via other ways, and are overall capitalist-planned.
Use audiobookshelf for audiobooks.