yardmaster vs dispatcher

yardmaster and dispatcher both are nouns.

Word	Noun	Adjective	Verb	Adverb
yardmaster	Yes	No	No	No
dispatcher	Yes	No	No	No

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

yardmaster: a railroad employer who is in charge of a railway yard
dispatcher: employee of a transportation company who controls the departures of vehicles according to weather conditions and in the interest of efficient service

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

yardmaster (noun)	dispatcher (noun)
a railroad employer who is in charge of a railway yard	the official who signals the beginning of a race or competition
	employee of a transportation company who controls the departures of vehicles according to weather conditions and in the interest of efficient service