undine vs water nymph

undine and water nymph both are nouns.

Word	Noun	Adjective	Verb	Adverb
undine	Yes	No	No	No
water nymph	Yes	No	No	No

As nouns, water nymph is a hypernym of undine; that is, water nymph is a word with a broader meaning than undine:

Other hypernyms of undine include water spirit, water sprite.

undine (noun)	water nymph (noun)
any of various female water spirits	(Greek mythology) any nymph of the water
	a fairy that inhabits water
	submerged aquatic plant having narrow leaves and small flowers; of fresh or brackish water
	a water lily having large leaves and showy fragrant flowers that float on the water; of temperate and tropical regions