What's the difference between epistolar and epistolary?

Epistolar

Definition:

Example Sentences:

Definition:

(a.) Pertaining to epistles or letters; suitable to letters and correspondence; as, an epistolary style.
(a.) Contained in letters; carried on by letters.

Example Sentences:

(1) The Matchmaker is a whimsical but miraculous piece – a staged version of the John B Keane epistolary novella that charts the efforts of a decent man to marry off achingly lonely country folk in the teeth of priestly disapproval.
(2) Wodehouse's correspondence is often clad in the epistolary equivalent of Bertie's heliotrope pyjamas, carefully buttoned up to disguise true feeling.
(3) Some of these were less well received than his earlier work, but La Silla del Águila (The Eagle's Throne, 2003), an epistolary novel comically taking apart the complexities and absurdities of Mexican political life, was seen by many critics as a return to form.
(4) A rare and expensive lot up for auction on eBay this week provides epistolary evidence that the man-who-will-be-king was once a hot-blooded young sailor with an eye for the ladies and a knack for flirtatious correspondence.
(5) After the first test performance, his friend Irving reportedly told Stoker that he never wanted to see the play again, prompting its re-imagining as the epistolary novel.
(6) Among Pacchioni's works, the "Dissertatio epistolaris de glandulis conglobatis Durae Meningis humanae" (1705) is particularly well known and contains the first description of arachnoidal granulations.
(7) In a letter to Marsh four days before his death he had written: "It's really my being lucky enough to bag an inch of candle that incites me to this pitch of punctual epistolary.