Boy Scout vs Cub Scout

Boy Scout and Cub Scout both are nouns.

Word	Noun	Adjective	Verb	Adverb
Boy Scout	Yes	No	No	No
Cub Scout	Yes	No	No	No

As nouns, Cub Scout is a hyponym of Boy Scout; that is, Cub Scout is a word with a more specific, narrower meaning than Boy Scout:

Other hyponyms of Boy Scout include Eagle Scout, rover, scouter, Sea Scout.

Boy Scout (noun)	Cub Scout (noun)
a boy who is a member of the Boy Scouts	a junior Boy Scout