Poison sumac (Toxicodendron vernix) and non-poisonous kinds such as Rhus glabra are distinct plants, despite sharing "sumac" in their common names. Unfortunately, the latter is often lumped together with the former, and its reputation suffers as a result.
That's too bad, because the "good" sumacs bear attractive fall foliage. Not that the bad kind doesn't: as you'll see in this picture showing what poison sumac looks like, the plant exhibits outstanding fall color. As it is with people, so it is with plants: even the bad ones tend to have something about them, at least, that's good.
But the confusion regarding which sumacs we have to watch out for and which ones are potentially useful at the sunny edge of a woodland garden illustrates two basic points: