singing voice vs vocalization

singing voice and vocalization both are nouns.

Word	Noun	Adjective	Verb	Adverb
singing voice	Yes	No	No	No
vocalization	Yes	No	No	No

As nouns, vocalization is a hypernym of singing voice; that is, vocalization is a word with a broader meaning than singing voice:

singing voice: the musical quality of the voice while singing
vocalization: the sound made by the vibration of vocal folds modified by the resonance of the vocal tract

Other hypernyms of singing voice include phonation, vocalisation, vocalism, voice, vox.

singing voice (noun)	vocalization (noun)
the musical quality of the voice while singing	the sound made by the vibration of vocal folds modified by the resonance of the vocal tract
	the use of uttered sounds for auditory communication