isolex vs heterogloss

isolex and heterogloss both are nouns.

Word	Noun	Adjective	Verb	Adverb
isolex	Yes	No	No	No
heterogloss	Yes	No	No	No

As nouns, heterogloss is a hypernym of isolex; that is, heterogloss is a word with a broader meaning than isolex:

isolex: an isogloss marking off the area in which a particular item of vocabulary is found.
heterogloss: the locative boundary of a certain linguistic feature, such as the pronunciation of a vowel, the meaning of a word, or use of some syntactic feature.

Other hypernyms of isolex include isogloss.

isolex (noun)	heterogloss (noun)
an isogloss marking off the area in which a particular item of vocabulary is found.	the locative boundary of a certain linguistic feature, such as the pronunciation of a vowel, the meaning of a word, or use of some syntactic feature.