Charybdis vs maelstrom

Charybdis and maelstrom both are nouns.

Word	Noun	Adjective	Verb	Adverb
Charybdis	Yes	No	No	No
maelstrom	Yes	No	No	No

As nouns, maelstrom is a hypernym of Charybdis; that is, maelstrom is a word with a broader meaning than Charybdis:

Charybdis: (Greek mythology) a ship-devouring whirlpool lying on the other side of a narrow strait from Scylla
maelstrom: a powerful circular current of water (usually the result of conflicting tides)

Other hypernyms of Charybdis include vortex, whirlpool.

Charybdis (noun)	maelstrom (noun)
(Greek mythology) a ship-devouring whirlpool lying on the other side of a narrow strait from Scylla	a powerful circular current of water (usually the result of conflicting tides)