Orthodox Christians celebrated the resurrection with a fire ceremony, cake and processions.

CHR Comment: The article describes the variety and pageantry of Orthodox Easter observed at numerous of locations. The different dates for observing Easter in western and eastern churches are due to the use of different calendars: the Gregorian in the West and the Julian in the East. The second link below describes the ruling about Easter from the Early Christian Council of Nicaea and provides an explanation of the two calendars that cause Christians to observe different dates for the feast.

Source: Orthodox Easter spreads “holy fire” around the world

http://catholicism.about.com/od/holydaysandholidays/f/Calculate_Date.htm