go away vs die off

go away and die off both are verbs.

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

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

go away (verb)	die off (verb)
get lost, as without warning or explanation	become extinct
go away from a place
move away from a place into another direction
become invisible or unnoticeable