plate armour vs sabaton

plate armour and sabaton both are nouns.

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

As nouns, sabaton is a hyponym of plate armour; that is, sabaton is a word with a more specific, narrower meaning than plate armour:

plate armour: specially hardened steel plate used to protect fortifications or vehicles from enemy fire
sabaton: armor plate that protects the foot; consists of mail with a solid toe and heel

plate armour (noun)	sabaton (noun)
specially hardened steel plate used to protect fortifications or vehicles from enemy fire	armor plate that protects the foot; consists of mail with a solid toe and heel
a historical type of personal armor made from iron or steel plates, which superseded mail during the 14th century.