sext vs message

sext and message both are nouns.

Word	Noun	Adjective	Verb	Adverb
sext	Yes	No	No	No
message	Yes	No	Yes	No

As nouns, message is a hypernym of sext; that is, message is a word with a broader meaning than sext:

sext: A message with sexual content
message: a communication (usually brief) that is written or spoken or signaled

sext (noun)	message (noun)
A message with sexual content	content communicating a message; what something is about
the fourth of the seven canonical hours; about noon	a communication (usually brief) that is written or spoken or signaled