Is there any primary difference between Irish Catholics and Roman Catholics, and if so, what?

Though many people nowadays pretend that the Celtic Church was seperate from Rome, this was a fallacy. Read St. Columbanas' letters to Pope Gregory The Great c550 to see how close the relationship was. The real differences were minor; monstaic rules, the dating of Easter (the big difference), how to take confession (public or private). They were resolved at the synod of Whitby c.650, as told in Bed's History of the English Church, where a vote was taken and the celtic rules lost. Since that time the Brit. Isles have always followed the Roman rite, BUT they have ALWAYS been in communion with Rome.

http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=000ARD

Although the term Irish Catholic predominantly refers to Catholics of Irish decent and Catholic inhabitants of Ireland, there was a period of time when Catholicism in that region of the world was isolated from the rest of the Roman Catholic Church. That means that some traditions unique to Ireland have developed in the church there.

https://en.wikipedia.org/wiki/Irish_Catholics

Today all Irish Catholics follow the leadership of the Roman Catholic church.

https://en.wikipedia.org/wiki/Roman_Catholicism_in_Ireland