manuscript vs codex

manuscript and codex both are nouns.

Word	Noun	Adjective	Verb	Adverb
manuscript	Yes	No	No	No
codex	Yes	No	No	No

As nouns, codex is a hyponym of manuscript; that is, codex is a word with a more specific, narrower meaning than manuscript:

manuscript: handwritten book or document
codex: an unbound manuscript of some ancient classic (as distinguished from a scroll)

Other hyponyms of manuscript include leaf-book, palimpsest, roll, scroll.

manuscript (noun)	codex (noun)
the form of a literary work submitted for publication	an unbound manuscript of some ancient classic (as distinguished from a scroll)
handwritten book or document	an official list of chemicals or medicines etc.