bombardon vs helicon

bombardon and helicon both are nouns.

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

As nouns, bombardon and helicon are synonyms defined as:

bombardon and helicon: a tuba that coils over the shoulder of the musician

bombardon (noun)	helicon (noun)
a large shawm; the bass member of the shawm family	a tuba that coils over the shoulder of the musician
a tuba that coils over the shoulder of the musician