dark red vs oxblood red

dark red and oxblood red both are nouns.

Word	Noun	Adjective	Verb	Adverb
dark red	Yes	No	No	No
oxblood red	Yes	No	No	No

As nouns, oxblood red is a hyponym of dark red; that is, oxblood red is a word with a more specific, narrower meaning than dark red:

Other hyponyms of dark red include burgundy, claret, wine-colored, wine-coloured, wine.

dark red (noun)	oxblood red (noun)
a red color that reflects little light	a dark brownish-red color