Easter Sunday, April 20. Observed in all Western Christian churches, Easter commemorates the Resurrection of Jesus. It is celebrated on the first Sunday after the full moon that occurs on or next after the vernal equinox (fixed at March 21) and is therefore celebrated between March 22 and April 25 inclusive. This date was fixed by the Council of Nicaea in A.D. 325.
Orthodox Easter (Pascha), Sun., April 20. The Orthodox Church uses
the Julian calendar when calculating Easter, rather than the more
contemporary Gregorian calendar. For this reason, Orthodox Easter
generally falls on a different date than the Western Christian
Easter, except this year the days coincide.