fundamentalist vs adherent

fundamentalist and adherent both are nouns.

Word	Noun	Adjective	Verb	Adverb
fundamentalist	Yes	Yes	No	No
adherent	Yes	Yes	No	No

As nouns, adherent is a hypernym of fundamentalist; that is, adherent is a word with a broader meaning than fundamentalist:

Other hypernyms of fundamentalist include disciple.

fundamentalist (noun)	adherent (noun)
a supporter of fundamentalism	someone who believes and helps to spread the doctrine of another
an adherent of fundamentalist principles

fundamentalist (adjective)	adherent (adjective)
of or relating to or characteristic of Protestant fundamentalism or its adherents	sticking fast
of or relating to or tending toward ideological fundamentalism