Socialism is a stage in historical development, one Marx referred to as “lower-stage communism.” Communism too is a stage in historical development. It isn’t necessarily that socialism lacks the aim to collectivize all production and distribution, it’s that socialism is that very gradual process of developing into a highly industrial society in all respects at which point this becomes feasible. Communism is the distinct mode of production and distribution where socialism has played its transitional role to completion.

As for the idea that we can skip socialism and go straight to communism, some fringe western Marxists believe this, but this is largely an anarchist conception as it runs counter to Marx.