chain armour vs ring mail

chain armour and ring mail both are nouns.

Word	Noun	Adjective	Verb	Adverb
chain armour	Yes	No	No	No
ring mail	Yes	No	No	No

As nouns, chain armour and ring mail are synonyms defined as:

chain armour and ring mail: (Middle Ages) flexible armor made of interlinked metal rings

Other synonyms of chain armour include chain armor, chain mail, mail, ring armor, ring armour.

chain armour (noun)	ring mail (noun)
(Middle Ages) flexible armor made of interlinked metal rings	(Middle Ages) flexible armor made of interlinked metal rings