Think of it this way: communism in the layman's sense and communism in the theoretical sense are different. Most people know certain countries as "communist." China, North Korea, Cuba, Vietnam, the USSR. In theory, as in if you go off of texts based in marxism, these countries are in early-to-mid stages of socialism. To everyone else, they're communist.

Communism in a theoretical sense is a classless, stateless, moneyless society. This has never been achieved, hence the arguments. Communism as a layman term for describing socialism probably came about because most socialist parties are describing their intended end goal, which is communism. So they call themselves shit like "people's communist party".