isotherm vs isopleth

isotherm and isopleth both are nouns.

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

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

isotherm: (meteorology) an isogram connecting points having the same temperature at a given time
isopleth: a line drawn on a map connecting points having the same numerical value of some variable

Other hypernyms of isotherm include isarithm, isogram.

isotherm (noun)	isopleth (noun)
(meteorology) an isogram connecting points having the same temperature at a given time	a line drawn on a map connecting points having the same numerical value of some variable