I think the reason for the apparent confusion comes from a few factors. Socialism pre-dated Karl Marx, but his work infused most strands of socialism going forward.
Communists still regarded themselves as socialist, and they pretty much share the same objectives; but communists would (mostly) regard revolution as the means to achieve them, whereas socialists (tend to) believe that they can do so within the democratic system.
The younger generation (those under 40) in North America, Europe (at least the western portion) etc., have mostly had no direct experience of the failures of left-wing economics; yet many of them have experienced issues arising from the failures of post-Cold War politics (student debt, housing crises etc.), and are susceptible to simplistic left-wing appeals (especially given that they are bombarded with throughout their education, by the media and through social media).
It is around thirty years since the end of the Cold War, and most of the left-wing parties had become less antagonistic towards capitalism; but the modernisers (such as Blair) failed and have been supplanted by the likes of Corbyn with the message that the failure was due to their abandonment of their traditional beliefs (think of it like religious revivalism). The difference, at least outside of the US, between today’s left and that of the '70s or earlier, is not that great economically; the difference, I would suggest, is that today’s left takes a much more radical view on societal issues - although, arguably, many nominally conservative parties are just as radical.
There is also the pragmatic situation post-1945, where the Soviet Union became (again) the main enemy of the western world. In that circumstance, emphasising the differences between socialists (most of whose voters were against the totalitarianism of the Soviets) and communists made sense.
The failure of any left-wing economy is always explained away using the “not true socialism/communism” argument, usually alongside an explanation that it is due to western sanctions.
It is not sustainable. National debts are sky high and growing across the west. The US or UK can kick the can down the road, at least for a time, with a degree of ease - provided they don’t do anything stupid. The Euro Zone has already witnessed the Greek crisis, but similar issues are likely to manifest themselves in larger economies such as Spain, Italy or even France at some point in the not too distant future.
I know that’s been a rather simplistic analysis, but you could write a book and not do the subject justice.