For the purposes of the Acoustic Performance credit:
Informal cafés or canteen areas, catering kitchens are generally services provided by an organisation such as a college, factory, or company for it’s students or staff.
Restaurants are places where food are served to the public on the premises. Compared to the above one, restaurants can be independent and not ancillary, as per the BREEAM definition and scope.
Bars are establishment where soft drink/alcohol and sometimes other refreshments are served. They might be on their own or auxiliary to other functions, eg hotels.