Socialism is the transition stage where collective ownership of the means of production, where the working class gains state power from the capitalist class.

Communism is a later stage of such abundance that money, classes and state power become redundant and are abolished.

The Culture is an imagining of the latter, where many means of production become people. They thus become workers that can labour for each other if they collectively decide to.

My reading of the Culture novels is that few people produce anything at all, or do any work or labour, and nearly every is produced by the ships, orbitals, and the Minds that control them. It’s not clear who exactly decides what gets produced, but decision making seems to be largely controlled by the Minds.

I don't remember which book it was in, exactly, but there is a conversation at one point with a Culture guy who is waiting tables, including cleaning them. He explains that a lot of humans actually do this kind of stuff, or, say, constructing spaceships, as a background from their "real" job-hobby (which is usually research or art) simply because completing things makes them happier, while cheerfully acknowledging that none of human labor in Culture is meaningful in the sense that it couldn't be done better and faster by machines. But it's still meaningful in a sense of giving people meaning.

The Minds are people too. Production happens individually at the small scale and based on collective decisions at the large scale. The Minds sway public opinion, but ultimately the public at large makes large decisions like the Idiran war.