In the case of ASL on BHD sun routes, they provide their own onboard crew, both flight deck and cabin. Aer Lingus typically provide a +1 in the cabin. The onboard service is Aer Lingus's in-flight catalogue, range and prices.
This differs from ASL 757's on 4 north Atlantic routes, where the aircraft, uniform and service are consistent with the Aer Lingus brand on its own fleet. Flight deck are ASL employed, cabin crew by Aer Lingus ...