leftist vs socialist

leftist and socialist both are nouns.

Word	Noun	Adjective	Verb	Adverb
leftist	Yes	Yes	No	No
socialist	Yes	Yes	No	No

As nouns, socialist is a hypernym of leftist; that is, socialist is a word with a broader meaning than leftist:

leftist (noun)	socialist (noun)
a person who belongs to the political left	a political advocate of socialism

leftist (adjective)	socialist (adjective)
believing in or supporting tenets of the political left	advocating or following the socialist principles