This is the city of Béal Feirste. Béal Feirste is an Irish city. The population are mostly Roman Catholic. They enjoy drinking and having a good time. Same-sex marriage and abortion are legal in Béal Feirste. Béal Feirste has no border with the EU, but has a hard border with the United Kingdom.
This is the city of Belfast. It is in the same place as Béal Feirste. Belfast is a British city. Its mostly Protestant population enjoy shouting “NO!”, marching and going to Church. Same-sex marriage, abortion and most kinds of sex are illegal in Belfast. Belfast has no border with the UK, but has a hard border with the EU.
There is no border between Béal Feirste and Belfast. The UK and EU Governments politely request that citizens of each city continue to pretend that the other one doesn’t exist.
Not much change, really.