ethnic joke vs joke

ethnic joke and joke both are nouns.

Word	Noun	Adjective	Verb	Adverb
ethnic joke	Yes	No	No	No
joke	Yes	No	Yes	No

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

Other hypernyms of ethnic joke include gag, jape, jest, laugh.

ethnic joke (noun)	joke (noun)
a joke at the expense of some ethnic group	a ludicrous or grotesque act done for fun and amusement
	activity characterized by good humor
	a triviality not to be taken seriously
	a humorous anecdote or remark intended to provoke laughter

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