You will find the details of the serial number including country of origin here. The first letter indicates the country in which they were printed; which is not necessarily the country in which they were first issued.
All Euro notes are issued in the name of the European Central Bank and bear the signature of J. C. Trichet. (or Wim Duisenberg for 2003 and earlier notes)
There is no difference in value; either as a currency or as notes and coin.
But the rules about legal tender differs from country to country. In France, all notes and coin are legal tender, whereas in Ireland, under the Economic and Monetary Union Act, 1998 "No person, other than the Central Bank of Ireland and such persons as may be designated by the Minister by order, shall be obliged to accept more than 50 coins denominated in euro or in cent in any single transaction."
Yes Purple - you got it in one. Even the ex editor Herr Max Hastings is now penning rubbish in that other stalworth of british journalism - the daily mail. I always thought that a newspaper license was only granted to bona fide news organs and not to peddlers of racism, xenophobia, sexism and suchlike. Although it's money pages are well regarded. Sorry for going off topic ....... just needed to vent