talk through one's hat vs sham

talk through one's hat is not a noun while sham is a noun.

Word	Noun	Adjective	Verb	Adverb
talk through one's hat	No	No	Yes	No
sham	Yes	Yes	Yes	No

As verbs, sham is a hypernym of talk through one's hat; that is, sham is a word with a broader meaning than talk through one's hat:

talk through one's hat: speak insincerely or without regard for facts or truths
sham: make believe with the intent to deceive

Other hypernyms of talk through one's hat include affect, dissemble, feign, pretend.

talk through one's hat (noun)	sham (noun)
	something that is a counterfeit; not what it seems to be
	a person who makes deceitful pretenses

talk through one's hat (adjective)	sham (adjective)
	adopted in order to deceive

talk through one's hat (verb)	sham (verb)
speak insincerely or without regard for facts or truths	make believe with the intent to deceive
	make a pretence of