bow-wow vs bark

bow-wow and bark both are nouns.

Word	Noun	Adjective	Verb	Adverb
bow-wow	Yes	No	No	No
bark	Yes	No	Yes	No

As nouns, bark is a hypernym of bow-wow; that is, bark is a word with a broader meaning than bow-wow:

bow-wow (noun)	bark (noun)
informal terms for dogs	a sailing ship with 3 (or more) masts
the bark of a dog	the sound made by a dog
	a noise resembling the bark of a dog
	tough protective covering of the woody stems and roots of trees and other woody plants