armour vs cataphract

armour and cataphract both are nouns.

Word	Noun	Adjective	Verb	Adverb
armour	Yes	No	Yes	No
cataphract	Yes	No	No	No

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

Other hyponyms of armour include body armor, body armour, coat of mail, suit of armor, suit of armour, buckler, shield.

armour (noun)	cataphract (noun)
tough more-or-less rigid protective covering of an animal or plant	armor that protects the wearer's whole body
protective covering made of metal and used in combat
a military unit consisting of armored fighting vehicles

armour (verb)	cataphract (verb)
equip with armor