USSR was eventually dissolved, people (including communists) don't consider China to be communist, the same goes for NK, and Venezuela. The only place where it seems to work is Cuba.
This is a distinction that is ideological rather than historical; none of these societies ever claimed to be communist. They all claimed they were actively in the process of building socialist economies, working towards the construction of a communist society down the line in the future. The USSR dissolved (for several reasons) and was replaced by modern capitalist Russia, China still claims it is building socialist economic forces working towards a communist future, as does Cuba.
Calling these societies "Communist" was an oversimplification of Western origin that was applied externally on these societies. These societies never were under the impression that they had built communism. They all said they were building socialism, a transitory state out of capitalism.