ring armour vs chain mail

ring armour and chain mail both are nouns.

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

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

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

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

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