in-joke vs jest

in-joke and jest both are nouns.

Word	Noun	Adjective	Verb	Adverb
in-joke	Yes	No	No	No
jest	Yes	No	Yes	No

As nouns, jest is a hypernym of in-joke; that is, jest is a word with a broader meaning than in-joke:

in-joke: a joke that is appreciated only by members of some particular group of people
jest: a humorous anecdote or remark intended to provoke laughter

Other hypernyms of in-joke include gag, jape, joke, laugh.

in-joke (noun)	jest (noun)
a joke that is appreciated only by members of some particular group of people	activity characterized by good humor
	a humorous anecdote or remark intended to provoke laughter

in-joke (verb)	jest (verb)
	act in a funny or teasing way
	tell a joke; speak humorously