yardmaster vs railroad man

yardmaster and railroad man both are nouns.

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

As nouns, railroad man is a hypernym of yardmaster; that is, railroad man is a word with a broader meaning than yardmaster:

Other hypernyms of yardmaster include dispatcher, railroader, railway man, railwayman, trainman.

yardmaster (noun)	railroad man (noun)
a railroad employer who is in charge of a railway yard	an employee of a railroad