blether vs piffle

blether and piffle both are nouns.

Word	Noun	Adjective	Verb	Adverb
blether	Yes	No	Yes	No
piffle	Yes	No	Yes	No

As verbs, piffle is a hypernym of blether; that is, piffle is a word with a broader meaning than blether:

Other hypernyms of blether include blab, blabber, chatter, clack, gabble, gibber, maunder, palaver, prate, prattle, tattle, tittle-tattle, twaddle.

blether (noun)	piffle (noun)
idle or foolish and irrelevant talk	trivial nonsense

blether (verb)	piffle (verb)
to talk foolishly	act in a trivial or ineffective way
	speak (about unimportant matters) rapidly and incessantly