attest vs show

attest is not a noun while show is a noun.

Word	Noun	Adjective	Verb	Adverb
attest	No	No	Yes	No
show	Yes	No	Yes	No

As verbs, show is a hypernym of attest; that is, show is a word with a broader meaning than attest:

attest: provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes
show: provide evidence for

Other hypernyms of attest include bear witness, evidence, prove, testify.

As verbs, show is a hypernym of attest; that is, show is a word with a broader meaning than attest:

attest (noun)	show (noun)
	an act or social event involving a public performance or entertainment
	pretending that something is the case in order to make a good impression
	something intended to communicate a particular impression

attest (verb)	show (verb)
authenticate, affirm to be true, genuine, or correct, as in an official capacity	establish the validity of something, as by an example, explanation or experiment
provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes	provide evidence for
give testimony in a court of law	indicate a place, direction, person, or thing; either spatially or figuratively
establish or verify the usage of	give expression to
	give evidence of, as of records
	indicate a certain reading; of gauges and instruments
	finish third or better in a horse or dog race
	show in, or as in, a picture
	take (someone) to their seats, as in theaters or auditoriums
	make visible or noticeable
	be or become visible or noticeable
	give an exhibition of to an interested audience