Book vs religious writing

Book and religious writing both are nouns.

Word	Noun	Adjective	Verb	Adverb
Book	Yes	No	No	No
religious writing	Yes	No	No	No

As nouns, religious writing is a hypernym of Book; that is, religious writing is a word with a broader meaning than Book:

Other hypernyms of Book include religious text, sacred text, sacred writing.

Book (noun)	religious writing (noun)
the sacred writings of the Christian religions	writing that is venerated for the worship of a deity
the sacred writings of Islam revealed by God to the prophet Muhammad during his life at Mecca and Medina