singing vs vocalizing

singing and vocalizing both are nouns.

Word	Noun	Adjective	Verb	Adverb
singing	Yes	Yes	No	No
vocalizing	Yes	No	No	No

As nouns, singing and vocalizing are synonyms defined as:

singing (noun)	vocalizing (noun)
the act of singing vocal music	the act of singing vocal music
disclosing information or giving evidence about another

singing (adjective)	vocalizing (adjective)
smooth and flowing