Recently Apple released "Sign in with Apple" / Apple Sign-in. This will supported starting from firmware 13.
As far as I remember, Apple also has "Game Center". The usage for this feature are includes saving game progress on cloud, Achievements, etc.
Android users might be familiar with Google Play Games. In Apple it was this "Game Center".
My question is, what is the difference between Apple Sign-in and Game Center? Is it only the firmware supported?
What is the difference between Game Center and Apple Sign-in?
Well, Game Center is for games. While Sign in with Apple is for your usual applications. You wouldn't take an effort to integrate Game Center in your Enterprise, Banking, Social Media Apps, would you?
Furthermore, Game Center is basically Apple's social gaming network. It uses a framework called Game Kit.
What does Game Kit do?
GameKit provides you with the ability to create apps that allow players to interact with each other. Multiplayer apps allow your game to create real-time network matches. Players can invite other players to join their game. Most importantly, players can receive invitations to join a match even when your game is not running. Your game is running on each device and the instances of your game exchange match and voice data with each other.
Lastly, Sign in with Apple is pretty much like your Sign in with Facebook or Google Sign in.
Sign in with Apple allows you to set up a user account in your system, complete with name, verified email address, and unique stable identifiers that allow the user to sign in to your app with their Apple ID. It works on iOS, macOS, tvOS, and watchOS. You can also add Sign in with Apple to your website or versions of your app running on other platforms. Once a user sets up their account, they can sign in anywhere you deploy your app.
docs:
Game Center: https://developer.apple.com/game-center/
Game Kit: https://developer.apple.com/documentation/gamekit/
Sign in with Apple: https://developer.apple.com/sign-in-with-apple/get-started/