High German vs West Germanic

High German and West Germanic both are nouns.

Word	Noun	Adjective	Verb	Adverb
High German	Yes	No	No	No
West Germanic	Yes	No	No	No

As nouns, West Germanic is a hypernym of High German; that is, West Germanic is a word with a broader meaning than High German:

High German: the standard German language; developed historically from West Germanic
West Germanic: a branch of the Germanic languages

Other hypernyms of High German include West Germanic language.

High German (noun)	West Germanic (noun)
the standard German language; developed historically from West Germanic	a branch of the Germanic languages