vocaliser vs alto

vocaliser and alto both are nouns.

Word	Noun	Adjective	Verb	Adverb
vocaliser	Yes	No	No	No
alto	Yes	Yes	No	No

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

vocaliser (noun)	alto (noun)
a person who sings	the pitch range of the lowest female voice
an organism that can utter vocal sounds	(of a musical instrument) the second highest instrument in a family of musical instruments
	the lowest female singing voice
	the highest adult male singing voice
	a singer whose voice lies in the alto clef

vocaliser (adjective)	alto (adjective)
	(of a musical instrument) second highest member of a group
	of or being the highest male voice; having a range above that of tenor
	of or being the lowest female voice