[_19qg]

> But the post I replied to implied that socialist=social democratic

That's actually largely the case in Western/Middle Europe.

> marxist/communists in the far-left parties (and sometimes the whole party)

Which are often not seen as socialist. Social/socialist typically signals that the party is inside the system supporting political spectrum. "communist/marxist" usually signals that the party is at least partly outside the system supporting political spectrum.