Primary/Secondary Shared Account means you share the account with 2 or more users. Using this account allows you to activate your playstation system as primary with the option "Change to this PS4" when it is available. IT IS POSSIBLE THAY YOU CANNOT NOT ACTIVATE YOUR PS4 AS PRIMARY. Price of this accounts is cheaper because sometimes the game may be occupied when you try to play online game modes. Tips for using shared accounts: Follow instructions sent after paying for a game to play offline (story modes and similar) without being disturbed by other users.