chatter vs blether

chatter and blether both are nouns.

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

As nouns, blether is a hyponym of chatter; that is, blether is a word with a more specific, narrower meaning than chatter:

Other hyponyms of chatter include chin music, idle talk, prate, prattle.

As verbs, blether is a hyponym of chatter; that is, blether is a word with a more specific, narrower meaning than chatter:

Other hyponyms of chatter include babble, blather, blither, smatter.

chatter (noun)	blether (noun)
noisy talk	idle or foolish and irrelevant talk
the high-pitched continuing noise made by animals (birds or monkeys)
the rapid series of noises made by the parts of a machine

chatter (verb)	blether (verb)
speak (about unimportant matters) rapidly and incessantly	to talk foolishly
talk socially without exchanging too much information
make noise as if chattering away
cut unevenly with a chattering tool
click repeatedly or uncontrollably