trainman vs trainmaster

trainman and trainmaster both are nouns.

Word	Noun	Adjective	Verb	Adverb
trainman	Yes	No	No	No
trainmaster	Yes	No	No	No

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

Other hyponyms of trainman include brakeman, signalman, yardman, train dispatcher, yardmaster.

trainman (noun)	trainmaster (noun)
an employee of a railroad	a railroad employer who is in charge of a railway yard