Historically speaking, socialism and communism are terms that are synonymous and interchangeable.

That is certainly not the case today, but the disagreement over terminology largely comes about as a result of state led suppression of communists and Red Scare tactics. As it became more dangerous to identify oneself as a communist the result was that it became more desirable/safer to identify as a socialist and also to argue that socialism was distinct from communism.

And while I’m no linguistic prescriptivist and I recognize that semantic drift happens to nearly all terminology over a long enough time frame, the issue with this changing definition is that it does not come out of any theoretical grounding or ideological framework. It is a reaction to external pressure, and that reaction by different groups and different peoples leads to the situation today where there is very little agreement or consensus regarding what people are referring to when they use these terms. They have been effectively rendered useless for the purposes of political discussion unless you first begin with a lengthy preamble about how you personally define these terms.

One popular way of making this distinction is the framing that Lenin used. He described socialism in terms of the international class struggle in the epoch of imperialism (the epoch we were currently living through). The jist is that the communist theory of “The State” is that it is definitionally an organ of class domination/class warfare. It is the instrument through which one set of class interests are enforced upon the rest of society, and during the epoch of imperialism that instrument of capitalist class domination is wielded on a global scale. Therefore, any communist party seeking to put an end to the tyranny of the capitalist class will necessarily need a plan for opposing the counter-revolution of the capitalist class and the inevitable sabotage, acts of war, and attempts of the re-domination of the working classes during the epoch of imperialism.

In other words, the working classes would require their own state organ to enforce the interests of the working classes and protect against capitalist reaction and domination. If we are talking about this in terms of the common framing of the “endpoint” of communism being a “stateless, classless” society*, the argument goes that you cannot immediately jump to a stateless society so long as capitalism still has a stranglehold over the majority of the world and imperialist nations are still empowered to wage class warfare across the globe.

This analysis of the strategy and tactics required for the liberation of the working class was referred to as socialism by Lenin. So in this framework, Socialism is the strategy a communist party uses on the path to communism. If you would like to argue that a communist party working towards communism is meaningfully distinct from being communist, you are free to do so. But the distinction is quite slim.

On the other end of the spectrum, you have people inside the imperial core who describe themselves as socialists, or more commonly democratic socialists, and what they mean when they call themselves socialist is, “I want the system to remain relatively unchanged, but we should distribute the fruits of our country’s imperial plunder more equitably by petitioning the capitalist state to administer more welfare and social programs such as universal healthcare.”

This variety of socialist has very little relation to the historical usage of the term, and comes about much more directly as a result of that Cold war/red scare reaction I mentioned above. I would argue that this kind of socialism is little more than a rebranding of liberalism, but that certainly qualifies it as being distinct from communism.

On this forum at least, if you see someone talking about socialism they are much more likely to be using a definition closer to the first definition than the second one.

(*The framing of communism as a stateless, classless, moneyless society is a very sloppy framing, but is sufficient for this discussion)