armor plate vs plate armour

armor plate and plate armour both are nouns.

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

As nouns, armor plate and plate armour are synonyms defined as:

armor plate and plate armour: specially hardened steel plate used to protect fortifications or vehicles from enemy fire

Other synonyms of armor plate include armor plating, armour plate, plate armor.

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	a historical type of personal armor made from iron or steel plates, which superseded mail during the 14th century.