Why is it so difficult to find clear, specific explanations of what communism, Marxism, and socialism actually entail, and how they differ from one another?

This post isn’t meant to be political but rather why has it always been hard to find specific and clear-cut definitions of each 3 of these things? Each person has a different point of view on what these things actually are and what they mean, or it just doesn’t make sense and missing out details. Anyone redditors who know about this topic, can you please explain what each of these means? I’m pretty new to political philosophy.