heretic vs castaway

heretic and castaway both are nouns.

Word	Noun	Adjective	Verb	Adverb
heretic	Yes	No	No	No
castaway	Yes	No	No	No

As nouns, castaway is a hypernym of heretic; that is, castaway is a word with a broader meaning than heretic:

heretic: a person who holds religious beliefs in conflict with the dogma of the Roman Catholic Church
castaway: a person who is rejected (from society or home)

Other hypernyms of heretic include Ishmael, outcast, pariah.

heretic (noun)	castaway (noun)
a person who holds religious beliefs in conflict with the dogma of the Roman Catholic Church	a shipwrecked person
a person who holds unorthodox opinions in any field (not merely religion)	a person who is rejected (from society or home)