Data is Beautiful

In the context of OP's graph, the two terms are presumably interchangeable. Otherwise, stuffing would be left out of the vegetarian column like in the case of the turkey. And besides normally being cooked in a carcass, the actual contents of the stuffing/dressing I've had were always vegetarian. OP's graph lists two different values for environmental impact of vegetarian vs non-vegetarian stuffing/dressing, meaning that the contents of the stuffing/dressing are different. The impact of the turkey is already accounted for in the turkey row. That number doesn't change if you stuff a bunch of bread in its abdominal cavity.