speak vs go on

speak and go on both are verbs.

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

As verbs, go on is a hyponym of speak; that is, go on is a word with a more specific, narrower meaning than speak:

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