The ecclesiastical full moon, taken from the tables, however, occurred on March 20, before the ecclesiastical equinox on March 21.
In the astronomical case, this full moon occurred after the equinox, but in the ecclesiastical case, it preceded the equinox.
There are three major differences between the ecclesiastical and the astronomical systems.
Inevitably, the date of Easter occasionally differs from a date that depends on the astronomical full moon and astronomical vernal equinox.
Following the ecclesiastical rules, Easter was not until the Sunday that followed the next ecclesiastical full moon (Wednesday, April 18) making Easter Sunday, April 22.