What are the differences and similarities between Communism and Marxism?

Both came out of the head of Karl Marx-similarity

Marxism is a term to refer to an abstraction – the philosophical system created by Karl Marx.
Communism is a term to refer to a concrete – the Marxist ideas in practice by people – difference.
Example- Christianity as an abstract notion, Catholicism as a form of practice of Christianity.

As @josie says, Marxism is one of several ways to implement Communism. Maoism is another type of Communism and so is the Israeli Kibbutz.

Marxism is a much broader term. It refers largely to a critical framework that has been extended across disciplines (e.g., neomarxism in feminism, conflict perspective in sociology, etc.). I guess you can say it, broadly, deals with class (I don’t necessarily mean social class) divisions and conflict to find insight.

Real communism has never really been tried. As soon as the Soviets took control of Russia they decided that they liked and deserved the power so Russia and the Soviet Union were born, just another dictatorship with a theoretical communist philosophy.

The U.S. is similar in that we nominally have a democratic, capitalist state. We actually have an oligarchy and sinking further away from democracy every time congress passes another law.

Doesn’t matter