airman vs aeronaut

airman and aeronaut both are nouns.

Word	Noun	Adjective	Verb	Adverb
airman	Yes	No	No	No
aeronaut	Yes	No	No	No

As nouns, aeronaut is a hypernym of airman; that is, aeronaut is a word with a broader meaning than airman:

Other hypernyms of airman include aviator, flier, flyer, adult male, man.

airman (noun)	aeronaut (noun)
a male who operates an aircraft	someone who operates an aircraft