heathen vs idolater

heathen and idolater both are nouns.

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

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

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

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

heathen (adjective)	idolater (adjective)
not acknowledging the God of Christianity and Judaism and Islam