plate armor vs body armour

plate armor and body armour both are nouns.

Word	Noun	Adjective	Verb	Adverb
plate armor	Yes	No	No	No
body armour	Yes	No	No	No

As nouns, body armour is a hypernym of plate armor; that is, body armour is a word with a broader meaning than plate armor:

plate armor: a historical type of personal armor made from iron or steel plates, which superseded mail during the 14th century.
body armour: armor that protects the wearer's whole body

Other hypernyms of plate armor include body armor, cataphract, coat of mail, suit of armor, suit of armour.

plate armor (noun)	body armour (noun)
specially hardened steel plate used to protect fortifications or vehicles from enemy fire	armor that protects the wearer's whole body
a historical type of personal armor made from iron or steel plates, which superseded mail during the 14th century.