The main advantages of ADF is that it creates a lot of files and folder itself and it takes care of itself. JDeveloper organizes those quickly and accurately. Read more https://www.techtravelhub.com/2012/04/adf-framework-and-jdeveloper-are.html
Now what is an Application?
An application is an bucket which holds all necessary files for a project. Let us see how to create a new application in ADF via JDeveloper.
Step-1. Click on File—>New
Step-2. Select Application from general categories. We can see different applications right side pane.
Step-3 Different types of applications can be produced by JDeveloper.
- Generic Application: Single application contains single project.all projects created using other framework and tool , falls under this category.
- Application through EAR: Single application, Projects from Enterprise Application Archive .
- Application Template: This is not exactly an application but a template. Later part of time this template can be used for any other application.
- Fusion Web Application(ADF): An application which is data driven based on ADFbc-ADF Business component or ADF faces
- Java Desktop Application: An application based on java swing and bean.
- Java Desktop Application(ADF): An application based on java swing having rich client application.It is having one project for client one for ADF model.
- Java EE Web Application: Creates data bound web application based on JSF,EJB,JPA etc.
In this post I will create a Fusion Web Application.
so select Fusion Web Application(ADF) and click OK.
Step-4 Provide application Name and you can provide application directory. Click on Next. 
Step-5 Select template if you want to use wizard based project.Click Next.
Step-6 select default package source root and output directory. Click on next
Step-7 same for view controller click on finish.
Now we have created a new application for our project.
This is indeed helpful Very innovative & great project! Thanks!