Really? Resurrection day can be before 14th Nisan, as in 2016 (Easter: 22.3./14th Nisan: 22.4.) or 2024 (31.3./22.4.), and most often it is after 14th Nisan, as in 2019 (14th Nisan: 19.04., Easter: 21.4.), so I conclude they might coincide in some years. Do You have a proof to the contrary?
And since the Jews celebrate the feast for one week, 2019 is an instance where Easter coincides with Jewish Passover (
pessakh).
This is not a question of East or West, it is a question of
language. Easter is "pascha" in Latin, and hence most Romanic languages have a term derived from that (e.g.French Pâques, Portuguese Páscoa, and Portugal is
very western
), and there are also several non-Romanic languages (e.g. Swedish påsk).
It were Celtic missionaries which used the word "Easter" to translate the name of this feast, and the Anglo-Saxon missionaries that worked in what is now western Germany carried this term into our language (Ostern - the sound change proves the term was derived from east ("Osten" in German). AFAIK no non-Germanic language uses this term, but rather "passah" or "feast of resurrection".