send in vs send out

send in and send out both are verbs.

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

As verbs, send out is a hypernym of send in; that is, send out is a word with a broader meaning than send in:

send in: mail in; cause to be delivered
send out: to cause or order to be taken, directed, or transmitted to another place

Other hypernyms of send in include send.

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