Shelling beans are ones you shell out of the pod and eat while they are still green and soft and fresh -- like fresh lima beans for example, or I think fava beans (which I've never grown nor eaten however).
Drying beans would be ones that you wait til the pod is all hard and dry and rattley, and shell out the dried beans and store them dry in a jar til you soak and cook them, like for chili or bean soup or whatever.
