vocal vs religious song

vocal and religious song both are nouns.

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

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

vocal (noun)	religious song (noun)
music intended to be performed by one or more singers, usually with instrumental accompaniment	religious music for singing
a short musical composition with words

vocal (adjective)	religious 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