hydroisohypse vs isogram

hydroisohypse and isogram both are nouns.

Word	Noun	Adjective	Verb	Adverb
hydroisohypse	Yes	No	No	No
isogram	Yes	No	No	No

As nouns, isogram is a hypernym of hydroisohypse; that is, isogram is a word with a broader meaning than hydroisohypse:

hydroisohypse: a line on a map connecting points of equal level on the piezometric surface.
isogram: a line drawn on a map connecting points having the same numerical value of some variable

Other hypernyms of hydroisohypse include isarithm, isopleth.

hydroisohypse (noun)	isogram (noun)
a line on a map connecting points of equal level on the piezometric surface.	a line drawn on a map connecting points having the same numerical value of some variable