Marxists and Anarchists have a different view of what the state is, and what class is. Marxists see the state as an implementation of class oppression, Anarchists see it as a tool of hierarchy.

As a consequence, Marxists see Communism as a fully publicly owned and planned, democratic government, while Anarchists want decentralized networks of Communes. For Marxists, the Anarchist solution retains class distinctions as each commune only has internal ownership and thus class is retained, while for Anarchists the Marxist solution retains the state as it retains hierarchy.

This struggle over analysis drives the major distinctions between each major school of Leftist thought.

A good thread on this.

They do, but people like unruffled see marxists as traitors