go away vs fall off

go away and fall off both are verbs.

Word	Noun	Adjective	Verb	Adverb
go away	No	No	Yes	No
fall off	No	No	Yes	No

As verbs, fall off is a hyponym of go away; that is, fall off is a word with a more specific, narrower meaning than go away:

go away (verb)	fall off (verb)
get lost, as without warning or explanation	fall heavily or suddenly; decline markedly
go away from a place	diminish in size or intensity
move away from a place into another direction	come off
become invisible or unnoticeable