What is the difference between the English (Ireland) and English (Ireland Euro) site cultures?

The difference is in the use of periods and commas for thousand and decimal separators.
 
 
For example:
 
One thousand two hundred and fifty-nine and ninety-nine cents.
 
 
English (Ireland) = 1,259.99 € (the comma is used as a thousands separator and the period as a decimal separator).

English (Ireland Euro) = 1.259,99 € (the period is used as a thousands separator and the comma as a decimal separator).