public speaking vs speech

public speaking and speech both are nouns.

Word	Noun	Adjective	Verb	Adverb
public speaking	Yes	No	No	No
speech	Yes	No	No	No

As nouns, speech is a hypernym of public speaking; that is, speech is a word with a broader meaning than public speaking:

Other hypernyms of public speaking include address.

public speaking (noun)	speech (noun)
delivering an address to a public audience	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