I have heard several different things, but how I currently understand it is that Communism is a post-socialism state in which goods are produced with such efficiency and surplus that money becomes worthless and class, labor, and the state are phased out. Is this wrong? Is there any difference at all? I am pretty new to leftism. TIA
It literally depends.
At the time when Marx came out, communism was basically treated like an arcane word for socialism. They were used interchangeably, up until Lenin tried to make a distinction and call his party the one true communists. In his definition, socialism was the stage post-capitalism and pre-communism, and this idea is typically carried on in M-L ideologies and ignored by others.
Then there was even more definition swapping by regions, because one sounded better or the other sounded too similar to another local movement and was a bad association.
Compare to now, where I'd say communism is typically interpreted as the movement which brings around a communist society, that is, a classless, stateless, moneyless socialist society. Socialism is interpreted as a society where the workers [own|control] the means of production. Or, one where property is held in common and private property (note: not personal property) is abolished.
The secret is, the terms are meaningless out of context. Even back in 1924 some guy compiled over 40 distinct definitions of 'socialism', and then the Cold War and USA happened.