infidel vs idolater

infidel and idolater both are nouns.

Word	Noun	Adjective	Verb	Adverb
infidel	Yes	No	No	No
idolater	Yes	No	No	No

As nouns, idolater is a hyponym of infidel; that is, idolater is a word with a more specific, narrower meaning than infidel:

Other hyponyms of infidel include paynim, idol worshiper, idoliser, idolizer.

infidel (noun)	idolater (noun)
a person who does not acknowledge your god	a person who worships idols