one or more user accounts at a time

If your organization's environment includes more than one BlackBerry® Domain instance, you can use this option if users move to a different area in your organization and you need to move the user accounts to a different BlackBerry Domain. You can move these user accounts in live mode.

all user accounts on a BlackBerry® Enterprise Server

You can use this option to upgrade your organization's environment in phases to the latest version of the BlackBerry Enterprise Server. You can move these user accounts in bulk mode.