How the spring equinox, the moon, and Passover determine Easter's date

Orthodox and Greek Catholic churches celebrate Easter on April 12, while the Catholic Church observed it on April 5. Easter's date is determined by the first Sunday after the full moon following the spring equinox, a calculation established in 325 AD. Different calendars cause date discrepancies. The Orthodox Church also requires Easter to be celebrated after the Jewish Passover, a rule Catholics sometimes do not follow, leading to varying celebration dates.