vocal vs love song

vocal and love song both are nouns.

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

As nouns, love song is a hyponym of vocal; that is, love song is a word with a more specific, narrower meaning than vocal:

vocal (noun)	love song (noun)
music intended to be performed by one or more singers, usually with instrumental accompaniment	a song about love or expressing love for another person
a short musical composition with words

vocal (adjective)	love 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