rebuke vs speech

rebuke and speech both are nouns.

Word	Noun	Adjective	Verb	Adverb
rebuke	Yes	No	Yes	No
speech	Yes	No	No	No

As nouns, speech is a hyponym of rebuke; that is, speech is a word with a more specific, narrower meaning than rebuke:

rebuke (noun)	speech (noun)
an act or expression of criticism and censure	the mental faculty or power of vocal communication
	(language) communication by word of mouth
	the act of delivering a formal spoken communication to an audience
	words making up the dialogue of a play
	a lengthy rebuke
	the exchange of spoken words
	your characteristic style or manner of expressing yourself orally
	something spoken

rebuke (verb)	speech (verb)
censure severely or angrily