tuba vs bombardon

tuba and bombardon both are nouns.

Word	Noun	Adjective	Verb	Adverb
tuba	Yes	No	No	No
bombardon	Yes	No	No	No

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

Other hyponyms of tuba include euphonium, helicon.

tuba (noun)	bombardon (noun)
the lowest brass wind instrument	a large shawm; the bass member of the shawm family
	a tuba that coils over the shoulder of the musician