basso vs basso profundo

basso and basso profundo both are nouns.

Word	Noun	Adjective	Verb	Adverb
basso	Yes	No	No	No
basso profundo	Yes	No	No	No

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

basso (noun)	basso profundo (noun)
the lowest adult male singing voice	a very deep bass voice
an adult male singer with the lowest voice