town vs boom town

town and boom town both are nouns.

Word	Noun	Adjective	Verb	Adverb
town	Yes	No	No	No
boom town	Yes	No	No	No

As nouns, boom town is a hyponym of town; that is, boom town is a word with a more specific, narrower meaning than town:

Other hyponyms of town include burg, cow town, cowtown, ghost town, hometown, Main Street, market town.

town (noun)	boom town (noun)
the people living in a municipality smaller than a city	a town enjoying sudden prosperity
an urban area with a fixed boundary that is smaller than a city
an administrative division of a county