chirp vs tweet

chirp and tweet both are nouns.

Word	Noun	Adjective	Verb	Adverb
chirp	Yes	No	Yes	No
tweet	Yes	No	Yes	No

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

chirp (noun)	tweet (noun)
a sharp sound made by small birds or insects	A post on the social media site Twitter
	a weak chirping sound as of a small bird

chirp (verb)	tweet (verb)
make high-pitched sounds	To post a message on Twitter; post tweets, i.e. short text messages on the popular social media website Twitter
sing in modulation	squeeze tightly between the fingers
	make a weak, chirping sound