laugh vs in-joke

laugh and in-joke both are nouns.

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

As nouns, in-joke is a hyponym of laugh; that is, in-joke is a word with a more specific, narrower meaning than laugh:

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

laugh (noun)	in-joke (noun)
the sound of laughing	a joke that is appreciated only by members of some particular group of people
a humorous anecdote or remark intended to provoke laughter
a facial expression characteristic of a person laughing

laugh (verb)	in-joke (verb)
produce laughter