blabber vs blab

blabber is a noun but blab is not a noun.

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

As verbs, blabber and blab are synonyms defined as:

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

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

blabber (noun)	blab (noun)
one who reveals confidential information to the police or other authority

blabber (verb)	blab (verb)
speak (about unimportant matters) rapidly and incessantly	divulge confidential information or secrets
	speak (about unimportant matters) rapidly and incessantly