springtide vs high water

springtide and high water both are nouns.

Word	Noun	Adjective	Verb	Adverb
springtide	Yes	No	No	No
high water	Yes	No	No	No

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

springtide: a greater than average tide occurring during the new and full moons
high water: the tide when the water is highest

Other hypernyms of springtide include high tide, highwater.

springtide (noun)	high water (noun)
a greater than average tide occurring during the new and full moons	the tide when the water is highest
a swelling rush of anything