railwayman vs railroad man

railwayman and railroad man both are nouns.

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

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

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

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