sign off vs discontinue

sign off and discontinue both are verbs.

Word	Noun	Adjective	Verb	Adverb
sign off	No	No	Yes	No
discontinue	No	No	Yes	No

As verbs, discontinue is a hypernym of sign off; that is, discontinue is a word with a broader meaning than sign off:

Other hypernyms of sign off include cease, give up, lay off, quit, stop.

sign off (verb)	discontinue (verb)
cease broadcasting; get off the air; as of radio stations	prevent completion
	put an end to a state or an activity
	come to or be at an end