fall away vs vanish

fall away and vanish both are verbs.

Word	Noun	Adjective	Verb	Adverb
fall away	No	No	Yes	No
vanish	No	No	Yes	No

As verbs, vanish is a hypernym of fall away; that is, vanish is a word with a broader meaning than fall away:

Other hypernyms of fall away include disappear, go away.

fall away (verb)	vanish (verb)
fall to a lower standard	get lost, as without warning or explanation
diminish in size or intensity	decrease rapidly and disappear
	cease to exist
	pass away rapidly
	become invisible or unnoticeable