What is the difference between APP2APP User-Authentication and Cloud-Authentication?

App2App User-Authentication: It's an integration that enables payment services (purchase/refund/check last transaction) on Nexi POS using either SoftPOS or MobilePOS. Authentication is managed by the user, who must log in and handle their credentials.

App2App Cloud-Authentication: Similar to the User Authentication mode as features, but authentication is managed via a backend-generated token, making the process seamless and invisible to the user.