At the most basic level, yes, I think that I do know the difference. However at a deeper level, I am not sure that anyone does, since there are no hard boundaries between them, there are large overlaps, and different people define them differently, often using very subjective judgments and values to reach their definitions.

Even in the most extreme cases, there are no hard edges. For example; many would say that, Stalinist Russia was as Communist as you can get, yet they pursued some very racist policies, usually regarded as a feature of Fascism. While many Fascist governments, even Nazi Germany for example, believed in creating full employment by government spending, fairly socialist. While the leader A. H. was a former speaker for the Communist party.

Viewed from a distance the extreme political wings often look very different, but when you start looking close they often start to look very alike. Someone once said that the political spectrum is not a line, but a circle. The one defining feature however that all the 'isms' have in common, except perhaps for democratic-socialism, is that they are all, in one way or another anti democratic.