There is no difference. Communists used to call the system they wanted social democracy. Communism advocated for democratic worker control of the state. Once communism is achieved the state would no longer exist and an anarchist communist global society would be formed. However since that idea is retarded it ends up being a dictatorship of a party. Lenin advocated for a vanguard for the early stages of socialism but it wasn't supposed to be a totalitarian one party system.

Democratic socialism is usually in reference to less radical parties who work within the parliamentary system and don't seek to abolish capitalism but reform it.

Many communists today support the authoritarian socialist system(referred to as Marxist-Leninism) because they've grown up in a world where that is synonymous with communism but it really just highlights the failures in the application of Marx's ideas.