railwayman vs railway man

railwayman and railway man both are nouns.

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

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

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

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