Hello Cyn. I don't think the times have anything to do with opening hours. These are regulated locally. In many parts of Europe (including the UK) there is now no restriction on bar opening times. In my youth it was otherwise. In the town I lived in they closed the pubs by law at 11:00 pm, in the next town over at 10:30, which caused some people to travel to my town for 30 minutes more drinking time.
Summer time starts and ends at exactly the same time throughout the EU. Click here for the actual regulations:
Article 2
From 2002 onwards, the summer-time period shall begin, in every Member State, at 1.00 a.m., Greenwich Mean Time, on the last Sunday in March.
Article 3
From 2002 onwards, the summer-time period shall end, in every Member State, at 1.00 a.m., Greenwich Mean Time, on the last Sunday in October.
Thus Summer Time ends at UK at 02:00 BST, In most of Europe at 03:00 CEST and in Eastern Europe at 04:00 EEST. That way there is not an odd hour when the time difference is different.