socialist vs leftist

socialist and leftist both are nouns.

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

As nouns, leftist is a hyponym of socialist; that is, leftist is a word with a more specific, narrower meaning than socialist:

Other hyponyms of socialist include Fabian, internationalist, Menshevik, collectivist, left-winger.

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

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