seer vs sibyl

seer and sibyl both are nouns.

Word	Noun	Adjective	Verb	Adverb
seer	Yes	No	No	No
sibyl	Yes	No	No	No

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

Other hyponyms of seer include augur, auspex, prophetess.

seer (noun)	sibyl (noun)
a person with unusual powers of foresight	(ancient Rome) a woman who was regarded as an oracle or prophet
an authoritative person who divines the future	a woman who tells fortunes
an observer who perceives visually