greave vs plate armor

greave and plate armor both are nouns.

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

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

greave: armor plate that protects legs below the knee
plate armor: specially hardened steel plate used to protect fortifications or vehicles from enemy fire

Other hypernyms of greave include armor plate, armor plating, armour plate, plate armour.

greave (noun)	plate armor (noun)
armor plate that protects legs below the knee	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	a historical type of personal armor made from iron or steel plates, which superseded mail during the 14th century.