What is the difference between an MVC Model object, a domain object and a DTO

Solution 1:

Domain and model objects are essentially the same, and may contain business logic. Depending on implementation, domain and DTO objects may be equivalent if you remove business logic from the model into a service class.

Often a key variant of the DTO is the View Model, which is used purely to transfer data between the domain model and the view, although often a View Model may contain logic, although this should be purely UI logic.

Solution 2:

The Domain and DTO can also be your "model" objects - you can have a view to render the details of the "Customer" domain object.

A domain object can have business logic to enforce the properties of the domain entity. validation is one such case. The domain object by itself does not contain persistence related methods, but it can have meta-data (like annotations) to support persistence

the POJO programming model makes it possible to use the same object as your domain, DTO and model objects - essentially, you will not be implemented any extraneous interfaces that will only apply to one layer but does not apply to others.