>>509401200
Derry is the only thing that Republicans call the county or Derry and City of Derry. The Protestant population calls it same too even though the official UK name is Londonderry. Catholics never say Londonderry at all.
>>509401404
Derry isn't a Province it's a county with a city in it of the same name. You might be on about the flag of the province of Ulster that's used by the Irish.