milk wagon vs wagon

milk wagon and wagon both are nouns.

Word	Noun	Adjective	Verb	Adverb
milk wagon	Yes	No	No	No
wagon	Yes	No	No	No

As nouns, wagon is a hypernym of milk wagon; that is, wagon is a word with a broader meaning than milk wagon:

milk wagon: wagon for delivering milk
wagon: any of various kinds of wheeled vehicles drawn by an animal or a tractor

Other hypernyms of milk wagon include waggon.

milk wagon (noun)	wagon (noun)
wagon for delivering milk	any of various kinds of wheeled vehicles drawn by an animal or a tractor
	a car that has a long body and rear door with space behind rear seat
	van used by police to transport prisoners
	a child's four-wheeled toy cart sometimes used for coasting