Same difference as there is between an Irish Roman Catholic Church and an Italian Roman Catholics Church...LANGUAGE AND TRADITIONS!
Well I don't think that is accurate.
It has only been less than 40 years since Latin rite Catholic churches in every nation stopped use the same liturgical language. And honestly there is very little difference in tradition between the Irish chruches and the Italian churches - perhaps you could list some. And you would never see the Irish Church break communion with the Italian Church - while it is not uncomon for different Orthodox jurisdictions and National Churches to break communion with each other.
Orthodoxy is much different.
The different national Churches are totally independent from each other, and though they share the same faith and are usually in liturgical communion with each other, they are self governed, use different languages, have different styles of chant, some different liturgical traditions, and different local Saints.
While Roman Catholicism has been very united over the centuries, under one faith, one authority, one litrugy, one language, one calendar of saints, etc. Only in the last 40 years have we seen the Roman Catholic Church so divided, by language, and even local traditions - that have been introduced with the various post-Vatican II liturgical reforms, often without the permission of the Vatican.