Song of Songs vs Canticle of Canticles

Song of Songs and Canticle of Canticles both are nouns.

Word	Noun	Adjective	Verb	Adverb
Song of Songs	Yes	No	No	No
Canticle of Canticles	Yes	No	No	No

As nouns, Song of Songs and Canticle of Canticles are synonyms defined as:

Song of Songs and Canticle of Canticles: an Old Testament book consisting of a collection of love poems traditionally attributed to Solomon but actually written much later

Other synonyms of Song of Songs include Canticles, Song of Solomon.

Song of Songs (noun)	Canticle of Canticles (noun)
an Old Testament book consisting of a collection of love poems traditionally attributed to Solomon but actually written much later	an Old Testament book consisting of a collection of love poems traditionally attributed to Solomon but actually written much later