machine gunner vs artilleryman

machine gunner and artilleryman both are nouns.

Word	Noun	Adjective	Verb	Adverb
machine gunner	Yes	No	No	No
artilleryman	Yes	No	No	No

As nouns, machine gunner and artilleryman are synonyms defined as:

Other synonyms of machine gunner include cannoneer, gunner.

machine gunner (noun)	artilleryman (noun)
a serviceman in the artillery	a serviceman in the artillery