Final answer:
Bark inlay grafting is the type where the scion is smaller than the stock, used commonly for repairing damaged trees or where the stock's diameter is significantly larger.
Step-by-step explanation:
The type of grafting in which the scion is smaller than the stock is known as bark inlay grafting. In this method, a smaller scion is inserted into a slit made in the bark of the stock. The scion needs to have buds and is often wrapped to ensure that it stays in place and can establish a vascular connection with the stock. This method is often used in repairing damaged trees or when the stock is much larger in diameter than the scion, which wouldn't fit in other types of grafts such as splice or saddle grafting.