armor vs cataphract

armor and cataphract both are nouns.

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

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

armor (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

armor (verb)	cataphract (verb)
equip with armor