chatter vs prattle

chatter and prattle both are nouns.

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

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

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

As verbs, chatter and prattle are synonyms defined as:

chatter and prattle: speak (about unimportant matters) rapidly and incessantly

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

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