tweet vs chirp

tweet and chirp both are nouns.

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

As nouns, chirp is a hypernym of tweet; that is, chirp is a word with a broader meaning than tweet:

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

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