Old Testament vs Book of Jeremiah

Old Testament and Book of Jeremiah both are nouns.

Word	Noun	Adjective	Verb	Adverb
Old Testament	Yes	No	No	No
Book of Jeremiah	Yes	No	No	No

Old Testament (noun)	Book of Jeremiah (noun)
the collection of books comprising the sacred scripture of the Hebrews and recording their history as the chosen people; the first half of the Christian Bible	a book in the Old Testament containing the oracles of the prophet Jeremiah