chain armor vs byrnie

chain armor and byrnie both are nouns.

Word	Noun	Adjective	Verb	Adverb
chain armor	Yes	No	No	No
byrnie	Yes	No	No	No

As nouns, byrnie is a hyponym of chain armor; that is, byrnie is a word with a more specific, narrower meaning than chain armor:

chain armor: (Middle Ages) flexible armor made of interlinked metal rings
byrnie: a long (usually sleeveless) tunic of chain mail formerly worn as defensive armor

Other hyponyms of chain armor include brigandine, habergeon, hauberk, gusset, voider.

chain armor (noun)	byrnie (noun)
(Middle Ages) flexible armor made of interlinked metal rings	a long (usually sleeveless) tunic of chain mail formerly worn as defensive armor