oneiromancer vs diviner

oneiromancer and diviner both are nouns.

Word	Noun	Adjective	Verb	Adverb
oneiromancer	Yes	No	No	No
diviner	Yes	No	No	No

As nouns, diviner is a hypernym of oneiromancer; that is, diviner is a word with a broader meaning than oneiromancer:

oneiromancer: someone who divines through the interpretation of dreams
diviner: someone who claims to discover hidden knowledge with the aid of supernatural powers

oneiromancer (noun)	diviner (noun)
someone who divines through the interpretation of dreams	someone who claims to discover hidden knowledge with the aid of supernatural powers