ring armor vs byrnie

ring armor and byrnie both are nouns.

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

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

ring 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 ring armor include brigandine, habergeon, hauberk, gusset, voider.

ring 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