express vs mail

express and mail both are nouns.

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

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

express: mail that is distributed by a rapid and efficient system
mail: the bags of letters and packages that are transported by the postal service

As verbs, mail is a hypernym of express; that is, mail is a word with a broader meaning than express:

Other hypernyms of express include post, send.

express (noun)	mail (noun)
rapid transport of goods	(Middle Ages) flexible armor made of interlinked metal rings
public transport consisting of a fast train or bus that makes only a few scheduled stops	a conveyance that transports the letters and packages that are conveyed by the postal system
mail that is distributed by a rapid and efficient 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

express (adjective)	mail (adjective)
not tacit or implied
without unnecessary stops

express (verb)	mail (verb)
articulate; either verbally or with a cry, shout, or noise	cause to be directed or transmitted to another place
give expression to	send via the postal service
serve as a means for expressing something
indicate through a symbol, formula, etc.
send by rapid transport or special messenger service
obtain from a substance, as by mechanical action
manifest the effects of (a gene or genetic trait)

express (adverb)	mail (adverb)
by express