isotach vs isogram

isotach and isogram both are nouns.

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

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

isotach: a line joining points with constant wind speed.
isogram: a line drawn on a map connecting points having the same numerical value of some variable

Other hypernyms of isotach include isarithm, isopleth.

isotach (noun)	isogram (noun)
a line joining points with constant wind speed.	a line drawn on a map connecting points having the same numerical value of some variable