gangster vs malefactor

gangster and malefactor both are nouns.

Word	Noun	Adjective	Verb	Adverb
gangster	Yes	No	No	No
malefactor	Yes	No	No	No

As nouns, malefactor is a hypernym of gangster; that is, malefactor is a word with a broader meaning than gangster:

gangster: a criminal who is a member of gang
malefactor: someone who has committed a crime or has been legally convicted of a crime

Other hypernyms of gangster include criminal, crook, felon, outlaw.

gangster (noun)	malefactor (noun)
a criminal who is a member of gang	someone who has committed a crime or has been legally convicted of a crime