Socialism

That's a rather reductive way to look at it. You can't just snap you fingers and go from capitalism to communism. In fact, a big part of the argument Marx makes is that communism will not be possible until productive forces are sufficiently developed. All these countries have communists in power, but they are in a socialist stage of development. Furthermore, the dominant global system is itself capitalist, which puts limits on what individual countries can accomplish internally.

Saying that they merely change the way capitalism is managed ignores a fundamental difference between the two. The goal of private enterprise is to create profit for the owners through appropriation of the value the labor of the workers creates. On the other hand, the primary goal of the state owned enterprise is to provide social value. In this scenario, the labor of the workers directly benefit society and workers themselves. So, while the social relations within the state owned enterprise may resemble those in private capitalist enterprise, their goals are very different.