greave vs armour plate

greave and armour plate both are nouns.

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

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

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

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

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