Originally Posted by
3Cforme
As Microwave points out the relevant difference is EU law due to the OP's EU origin airport. It's also EU law that shifts responsibility from ticketing party (IATA standard) to operating carrier here.
However, the problem with EC261 is that it doesn't provide much protection for schedule changes and cancellations that occur more than two weeks in advance of the travel date. A carrier can fulfill the obligation by just giving a full refund, which isn't much help when the passenger must then purchase much more expensive alternate tickets.