How was socialism different from Marxist?

Socialism is an economic system based on public or cooperative ownership of the means of production, worker's self-management and collective decision-making in enterprises, and production for use.

Marxism is an economic and sociological theory on capitalism, economic development and social class that predicts socialism to be an outcome of economic and technological development.

Many socialists agreed with Marxist or quasi-Marxist analysis and theories, but not all socialists agree with or are Marxist. In short, Marxism is a theory; Socialism is a system.