What is the difference in changing the scope between a spiral approach and a waterfall approach?

Ans) The scope of needs changes in Waterfall model is less than that in Spiral Model. In Waterfall model, you progress to the next phase only when the needs of the stage above it are finalized and signed off. So literally, we do not have any scope of changing the needs once we move down the phases in this model.

Though, Spiral model gives us flexibility to change the needs and scope anytime during the life cycle.

In this model, we execute the individual requirements following all the standard phases of Software Life Cycle. Thus, if any new change is there, we can execute it in next version of the software.