Okay, first, to lay some groundwork, there have been many modes of production throughout history
first, there was hunter/gatherer societies, then feudalism, then capitalism
Then we have theories as to what could come next, according to the marxist viewpoint, the next thing will be socialism, and then after that, communism.
So, communism is a post-socialist ideology, the only requirement for it to be socialism is that instead of a bourgeois class and a worker class, they will become unified (doesn’t matter how for the purposes of explaining this, but usually through violent revolution)
So, a socialist place would have the workers self-manage, people who work in a place would also have democratic control over that place in some way.
After that happens, for various reasons outside of the scope of an eli5, communism comes, communism is a post-socialist society in which the workers own the means of production (hence the socialist prerequisite), currency has been abolished, the state has been abolished (but not government, these are two distinct entities in socialist thought), and there are no class divisions whatsoever.
Part of the problems with discussions about these topics is that communist philosophers of old used terms in very different ways than the colloquial ways we use them today. I can expand upon this if you have any followup questions!