A Domain Object that implements the Domain functionality (or concept) that may not be modeled (naturally) as a behavior in any domain entity or value object
A Domain Object that does NOT implement any Domain functionality but depends on other Domain Objects | Services for exposing higher-level domain functionality to the consumers external to the model.
Implementation of a behavior that is not a core domain behavior
The illustration below shows an application service CustomerPortfolio that uses multiple enttities to create a consolidated view of the customer.