mail vs cataphract

mail and cataphract both are nouns.

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

As nouns, cataphract is a hypernym of mail; that is, cataphract is a word with a broader meaning than mail:

Other hypernyms of mail include body armor, body armour, coat of mail, suit of armor, suit of armour.

mail (noun)	cataphract (noun)
(Middle Ages) flexible armor made of interlinked metal rings	armor that protects the wearer's whole body
a conveyance that transports the letters and packages that are conveyed by the postal system
the system whereby messages are transmitted via the post office
the bags of letters and packages that are transported by the postal service
any particular collection of letters or packages that is delivered

mail (verb)	cataphract (verb)
cause to be directed or transmitted to another place
send via the postal service