Karl Marx described Communism in his works. That was built in Soviet Russia is Socialism that is a different order, even if it was presented as the transitional stage (that never ended).

Communism as described in "Manifest" includes abolishement of money, abolishement of the family institution, no nationalities,  no right of inheritance and some other very radical steps that were not implemented. Socialism is no longer Capitalism but retains more similarly. While services like health, education and transportation were free or cheap, there were still money and salaries. Family was not touched. One single party remained, it should be no any under Communism.

The differences between these two societies seem well defined in Lenin's works. Soviet Union never claimed it has built exactly Communism, addressing the mentioned differences itself.