hard core vs ingroup

hard core and ingroup both are nouns.

Word	Noun	Adjective	Verb	Adverb
hard core	Yes	No	No	No
ingroup	Yes	No	No	No

As nouns, ingroup is a hypernym of hard core; that is, ingroup is a word with a broader meaning than hard core:

hard core: the most dedicated and intensely loyal nucleus of a group or movement
ingroup: an exclusive circle of people with a common purpose

Other hypernyms of hard core include camp, clique, coterie, inner circle, pack.

hard core (noun)	ingroup (noun)
the most dedicated and intensely loyal nucleus of a group or movement	an exclusive circle of people with a common purpose