App Registration one form or several forms?

1. What is the difference between enterprise application and app registration?
2. What is an app registration?

What is the difference between enterprise application and app registration?

In some cases, people even use both terms interchangeably. But, App registration is simply the actual application object where you configure application settings. Whereas Enterprise Application is a representation of the application within a directory.

What is an app registration?

What is an Application Registration. The application registration in your tenant enables you and others to authenticate against your Azure Active Directory. Another option is to authentication through an application secret.