informal vs epistolary

informal and epistolary both are adjectives.

Word	Noun	Adjective	Verb	Adverb
informal	No	Yes	No	No
epistolary	No	Yes	No	No

informal (adjective)	epistolary (adjective)
not formal	written in the form of or carried on by letters or correspondence
used of spoken and written language
having or fostering a warm or friendly and informal atmosphere
not officially recognized or controlled