Book vs sacred writing

Book and sacred writing both are nouns.

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

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

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

Book (noun)	sacred 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