https://www.timeanddate.com/calendar/determining-easter-date.html
In 325CE the Council of Nicaea established that Easter would be held on the first Sunday after the first Full Moon occurring on or after the vernal equinox.(*) From that point forward, the Easter date depended on the ecclesiastical approximation of March 21 for the vernal equinox.
Easter is delayed by 1 week if the Full Moon is on Sunday, which decreases the chances of it falling on the same day as the Jewish Passover. The council’s ruling is contrary to the Quartodecimans, a group of Christians who celebrated Easter on the day of the Full Moon, 14 days into the month.
Comparative calendars
Not all Christian churches observe Easter according to the Gregorian calendar. Some churches still observe Easter under the Julian calendar.
The Gregorian calendar was created because the Julian calendar was slightly too long. With the Julian calendar, the equinox date moved towards the earlier dates of March and further away from the Easter. Therefore, the introduction of the Gregorian calendar allowed for a realignment with the equinox.
Is there a perfect calendar?
In the Gregorian calendar, Easter falls on a Sunday between March 22 and April 25 from 1753 to 2400. In the Julian calendar, used by some eastern or Orthodox churches, Easter also falls on a Sunday from March 22 to April 25, which in the Gregorian calendar are from April 3 to May 10 from 1753 to 2400.
In 2007 Easter fell on the same date (April 8) in both calendars when the Julian date was converted to the Gregorian date. This also happened in other years, such as 2004, 2010 and 2011.
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TL;DR: The dating is a matter of relative time measurement and practicality. It is not something which contributes to "schism" any more than the dating of Christmas Day.