railway man vs railwayman

railway man and railwayman both are nouns.

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

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

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

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