speech vs speech act

speech and speech act both are nouns.

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

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

speech (noun)	speech act (noun)
the mental faculty or power of vocal communication	the use of language to perform some act
(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