piffle vs blab

piffle is a noun but blab is not a noun.

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

As verbs, piffle and blab are synonyms defined as:

piffle and blab: speak (about unimportant matters) rapidly and incessantly

Other synonyms of piffle include blabber, chatter, clack, gabble, gibber, maunder, palaver, prate, prattle, tattle, tittle-tattle, twaddle.

piffle (noun)	blab (noun)
trivial nonsense

piffle (verb)	blab (verb)
act in a trivial or ineffective way	divulge confidential information or secrets
speak (about unimportant matters) rapidly and incessantly	speak (about unimportant matters) rapidly and incessantly