body armour vs coat of mail

body armour and coat of mail both are nouns.

Word	Noun	Adjective	Verb	Adverb
body armour	Yes	No	No	No
coat of mail	Yes	No	No	No

As nouns, body armour and coat of mail are synonyms defined as:

body armour and coat of mail: armor that protects the wearer's whole body

Other synonyms of body armour include body armor, cataphract, suit of armor, suit of armour.

body armour (noun)	coat of mail (noun)
armor that protects the wearer's whole body	armor that protects the wearer's whole body