pressman vs compositor

pressman and compositor both are nouns.

Word	Noun	Adjective	Verb	Adverb
pressman	Yes	No	No	No
compositor	Yes	No	No	No

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

Other hyponyms of pressman include setter, typesetter, typographer, proofreader, reader.

pressman (noun)	compositor (noun)
someone whose occupation is printing	one who sets written material into type
a male journalist employed to provide news stories for newspapers or broadcast media