Difference Between Remote Desktop and mstsc /console

In Windows Server 2003, when you use Terminal Services, you can connect to the console session (session 0), and at the same time, open a shadow session to it (as long as you connect from a session other than the console). With this added functionality, you can log on to a Windows Server 2003-based server that is running Terminal Services remotely and interact with session 0 as if you were sitting at the physical console of the computer. This session can also be shadowed so that the remote user and the local user at the physical console can see and interact with the same session.

While for normal Remote Desktop Connection, the session will remained in remote computer after user disconnected. However, the user will not be able to login to continue that session. The user need to manually connect back to that session.

"The user domain\username is logged locally on to this computer. The user has been idled for number minutes. The desktop is unlocked. If you continue, this user's session will end and any unsaved data will be lost."

Normal remote desktop command,

mstsc {target_computer_name}

Remote desktop to console session,

mstsc /console {target_computer_name}

http://support.microsoft.com/kb/278845