New calendarists
The new calendarists are Eastern Orthodox churches that adopted the Revised Julian calendar—namely the Orthodox churches of Constantinople, Alexandria, Antioch, Bulgaria, Greece, Cyprus, Romania, Czech and Slovak Orthodox Church, Albania, the Estonian Apostolic Orthodox Church, and most of the Orthodox Church in America.
Most churches that still use the Julian calendar remain in communion with the new calendarists: the Orthodox churches of Jerusalem, Russia, Serbia, Georgia, Ukraine, Ukrainian Orthodox Church (Moscow Patriarchate), and Mount Athos.
Old Calendarists
The apparently contrasting term Old Calendarists in fact does not refer to all churches that use the old calendar, but only those that are not in communion with the rest of Eastern Orthodoxy. They include the Greek Old Calendarists and some Russian Old Believers.(Clogg 2002, pp. 8-9)
References
- Clogg, Richard (2002). Minorities in Greece: Aspects of a Plural Society. C. Hurst & Co. Publishers. ISBN 978-1-85065-705-7.CS1 maint: ref=harv (link)