BlackBerry ID is a master key to the BlackBerry store, applications, and web services. You can use it to access all of your previously used passwords, including BlackBerry Messenger.
What is a BBM account?
BlackBerry ID is a master key that unlocks BlackBerry products, websites, services, and applications, including BlackBerry Protect, BlackBerry World storefront and BlackBerry Messenger. It allows users to access any BlackBerry product that supports BlackBerry ID.