chain armour vs hauberk

chain armour and hauberk both are nouns.

Word	Noun	Adjective	Verb	Adverb
chain armour	Yes	No	No	No
hauberk	Yes	No	No	No

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

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

Other hyponyms of chain armour include brigandine, habergeon, byrnie, gusset, voider.

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