send out vs mail out

send out and mail out both are verbs.

Word	Noun	Adjective	Verb	Adverb
send out	No	No	Yes	No
mail out	No	No	Yes	No

As verbs, mail out is a hyponym of send out; that is, mail out is a word with a more specific, narrower meaning than send out:

send out: to cause or order to be taken, directed, or transmitted to another place
mail out: transmit by mail

Other hyponyms of send out include send in, get off, mail.

send out (verb)	mail out (verb)
to cause or order to be taken, directed, or transmitted to another place	transmit by mail