Both stuffing and dressing are side dish items that traditionally accompany poultry such as turkey or chicken. They are usually served during the Thanksgiving and Christmas holiday seasons, and have a couple of differences.
The key difference between dressing and stuffing is the method of preparation. Dressing can be prepared separately from the bird on the stove top, either from scratch or a store-bought mix. Stuffing, however, is made by stuffing the mixture into the cavity of the bird and cooking them in the oven together.
Another difference between stuffing and dressing is in the time needed to prepare it. Stuffing inside the bird must be cooked as long as the bird needs to cook, and also increases the cooking time of the bird. Dressing can be made quickly on the stove top or in the oven; either way it will take less time than stuffing.
Stuffing made inside the bird can pick up flavors from the bird and impart flavors to the bird. This may be desirable or undesirable depending on the method of preparing the bird. The flavor of dressing depends solely on its ingredients.