trainman vs railroad man

trainman and railroad man both are nouns.

Word	Noun	Adjective	Verb	Adverb
trainman	Yes	No	No	No
railroad man	Yes	No	No	No

As nouns, trainman and railroad man are synonyms defined as:

Other synonyms of trainman include railroader, railway man, railwayman.

trainman (noun)	railroad man (noun)
an employee of a railroad	an employee of a railroad