isobase vs isopleth

isobase and isopleth both are nouns.

Word	Noun	Adjective	Verb	Adverb
isobase	Yes	No	No	No
isopleth	Yes	No	No	No

As nouns, isopleth is a hypernym of isobase; that is, isopleth is a word with a broader meaning than isobase:

isobase: a line drawn on a map or chart connecting places of equal or constant land upheaval.
isopleth: a line drawn on a map connecting points having the same numerical value of some variable

Other hypernyms of isobase include isarithm, isogram.

isobase (noun)	isopleth (noun)
a line drawn on a map or chart connecting places of equal or constant land upheaval.	a line drawn on a map connecting points having the same numerical value of some variable