What's the difference between panegyric and panegyris?

Panegyric

Definition:

(a.) An oration or eulogy in praise of some person or achievement; a formal or elaborate encomium; a laudatory discourse; laudation. See Synonym of Eulogy.
(a.) Alt. of Panegyrical

Example Sentences:

(1) While the court poets still compose panegyrics beyond the walls of his palace, his power is fading.
(2) Campaigner Jessica Panegyres said the 2050 reef plan paid “lip service to reef protection” and did little to deal with the issue of climate change.
(3) "The BBC exists above all on trust and the relationship between the wider public and the BBC itself," according to one of Chris Patten's panegyrics last week.
(4) So, The Doctor's Dilemma was, in a sense, a launch pad for Danny Boyle's panegyric to the NHS.
(5) Catherine Rose Olney, Buckinghamshire • The debate on the Scottish referendum has been littered with the panegyrics to the union from the Westminster-based politicians.