text vs missive

text and missive both are nouns.

Word	Noun	Adjective	Verb	Adverb
text	Yes	No	Yes	No
missive	Yes	No	No	No

As nouns, missive is a hyponym of text; that is, missive is a word with a more specific, narrower meaning than text:

text (noun)	missive (noun)
the words of something written	a written message addressed to a person or organization
the main body of a written work (as distinct from illustrations or footnotes etc.)
a book prepared for use in schools or colleges
a passage from the Bible that is used as the subject of a sermon

text (verb)	missive (verb)
to send a message by SMS or similar text-based messaging service