go on vs speak

go on and speak both are verbs.

Word	Noun	Adjective	Verb	Adverb
go on	No	No	Yes	No
speak	No	No	Yes	No

As verbs, speak is a hypernym of go on; that is, speak is a word with a broader meaning than go on:

Other hypernyms of go on include talk.

go on (verb)	speak (verb)
come to pass	express in speech
continue talking	exchange thoughts; talk with
start running, functioning, or operating	use language
move forward, also in the metaphorical sense	give a speech to
continue a certain state, condition, or activity	make a characteristic or natural sound