Q.

What is different between Guest account and  linked  account? 

 A.

The Guest account can run game in the same way as the linked account.

However, the information of the Guest account is stored inside of the device.

So, the Guest account may be deleted when you delete and reinstall   the game o r change the device etc.

During running the game with Guest account, if the account is deleted, we cannot give you any help including the restoration. Please ask for your understanding. 

So, protecting account information, please we recommend that you run the game after the connection of the account.