go off vs fall in

go off and fall in both are verbs.

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

As verbs, fall in is a hypernym of go off; that is, fall in is a word with a broader meaning than go off:

Other hypernyms of go off include break, cave in, collapse, founder, give, give way.

go off (verb)	fall in (verb)
be discharged or activated	break down, literally or metaphorically
happen in a particular manner	become part of; become a member of a group or organization
burst inward	to take one's place in a military formation or line
go off or discharge
stop running, functioning, or operating
run away; usually includes taking something or somebody along