High-level overview
App model
The app model is an object provided by the application developer. It can be a JSON object fetched from the server, or some object constructed on the client side. Angular doesn't make any assumptions about it.
Form model
The form model is a UI-independent representation of a form. It consists of three building blocks: FormControl, FormGroup, and FormArray. We will look at the form model in detail later in this chapter. Both FormsModule and ReactiveFormsModule use this model.