neap tide vs high water

neap tide and high water both are nouns.

Word	Noun	Adjective	Verb	Adverb
neap tide	Yes	No	No	No
high water	Yes	No	No	No

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

neap tide: a less than average tide occurring at the first and third quarters of the moon
high water: the tide when the water is highest

Other hypernyms of neap tide include high tide, highwater.

neap tide (noun)	high water (noun)
a less than average tide occurring at the first and third quarters of the moon	the tide when the water is highest