tide vs high water

tide and high water both are nouns.

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

As nouns, high water is a hyponym of tide; that is, high water is a word with a more specific, narrower meaning than tide:

tide: the periodic rise and fall of the sea level under the gravitational pull of the moon
high water: the tide when the water is highest

tide (noun)	high water (noun)
the periodic rise and fall of the sea level under the gravitational pull of the moon	the tide when the water is highest
something that may increase or decrease (like the tides of the sea)
there are usually two high and two low tides each day