explanation vs speech act

explanation and speech act both are nouns.

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

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

explanation (noun)	speech act (noun)
thought that makes something comprehensible	the use of language to perform some act
a statement that makes something comprehensible by describing the relevant structure or operation or circumstances etc.
the act of explaining; making something plain or intelligible