Catholic Easter ping!
Both East and West calculate Easter/Pashca the same, but due to some Orthodox still using the Old Calendar, frequently the calculation of the "Equinox" (that must be after March 25) is different and therefore the Easter date is different as well. It really has nothing to do with Passover; East and West treat that the same.
Since all canonical Orthodox want to use the same date, the New Calendarists defer to the Old.
The Holy Fire appears in the Holy Sepulcher on the date of Orthodox Pascha, so obviously that date is correct.
I am just kidding, but I think this is one area that East and West could find a good Ecumenical solution.