Box 1: An Azure AD app registration
Azure active directory (AD) provides cloud based directory and identity management services.You can use azure AD to manage users of your application and authenticate access to your applications using azure active directory.
You register your application with Azure active directory tenant.
Box 2: A conditional access policy
Conditional Access policies at their simplest are if-then statements, if a user wants to access a resource, then they must complete an action.
By using Conditional Access policies, you can apply the right access controls when needed to keep your organization secure and stay out of your user's way when not needed.
Reference:
https://codingcanvas.com/using-azure-active-directory-authentication-in-your-web-application/
https://docs.microsoft.com/en-us/azure/active-directory/conditional-access/overview
