send out vs send in

send out and send in both are verbs.

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

As verbs, send in is a hyponym of send out; that is, send in 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
send in: mail in; cause to be delivered

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

send out (verb)	send in (verb)
to cause or order to be taken, directed, or transmitted to another place	mail in; cause to be delivered
	give one's name or calling card to a servant when making a formal visit