The default printer is that printer that is set as the default when installed on the workstation during user logs in.
The temporary printer is installed when the user logs in and removed when the workstation is rebooted. This is useful when a user logs in to the network using a guest account, and you want the printer to be removed when the user is done.
For more information on how to set a default printer and temporary printers, see How to manage the printers for iCM users?