Rhus copallinum, Winged Sumac
The leaf stalk is winged.
Common in the Piedmont and coastal plain. Up to 15' tall.

Rhus typhina, Hairy Sumac
The leaf stalk and inflorescense stalk are hairy, as is the bright red fruit.
Common in the Piedmont, rare on the coastal plain. Up to 30' tall.

Rhus glabra, Smooth Sumac
The leaf stalk is neither winged nor hairy.
Common in the Piedmont, rare on the coastal plain. Up to 15' tall.

The accepted name for Rhus vernix, poison sumac, is now Toxicodendron vernix.

Sources: The Flora of Delaware, Woody Plants of Maryland.