Black Vultures have white primaries (Turkey Vultures have white secondaries and primaries) and a black head. The tail is shorter and more triangle shaped. When soaring they hold their wings in less of a dihedral than Turkey Vultures. They also seem to flap a lot more.
Black Vultures tend to form really large roosts in the trees with a few Turkey Vultures mixed in. There is a large roost in Brazos Bend State Park near the interpetive center
A breeding range map is available form the Breeding Bird Survey
A winter range map is available from the Christmas Bird Count