"A 'Dead End' sign is used at the entrance of a single street that terminates in a dead end or a cul-de-sac. A 'No Outlet' sign is used at the entrance to a road network from which there is no other exit, for example, when a small neighborhood composed of several streets has only one entrance on to an arterial street."
It's not just Virginia. Seems to be nationwide.
http://www.seattlepi.com/local/transportation/article/Getting-There-The-difference-between-dead-end-961940.php