vocal vs song

vocal and song both are nouns.

Word	Noun	Adjective	Verb	Adverb
vocal	Yes	Yes	No	No
song	Yes	No	No	No

As nouns, vocal and song are synonyms defined as:

vocal (noun)	song (noun)
music intended to be performed by one or more singers, usually with instrumental accompaniment	the act of singing
a short musical composition with words	a short musical composition with words
	the characteristic sound produced by a bird
	a distinctive or characteristic sound
	a very small sum

vocal (adjective)	song (adjective)
having or using the power to produce speech or sound
relating to or designed for or using the singing voice
given to expressing yourself freely or insistently
full of the sound of voices