The USSR was a Union of Soviet Socialist Republics. It was headed by a Communist Party, ie a party trying to build towards Communism, but through Socialism. The end-goal of Socialism is to eventually do away with the state, class, and money, as all 3 are used to oppress people, creating Communism. Same with Cuba.
Sweden is not Socialist, it’s a Social Democracy. The mode of production is Capitalism, with expanded social safety nets. Some industries are nationalized, but Capital is largely in the hands of Capitalists, not shared among Workers. Actual Democratic Socialism would be like if Sweden’s Unions took ownership of all Industry, but maintained government structures.
I hope that clears things up! What you call Communism, is in fact a specific form of Marxist-Leninist Socialism, most likely.