She is taller because of her ears. It happens just like how some people are taller because of the hair.
They are the same size, technically they can wear each other’s clothes, as intended. He looks so stoic the way he is, decided not to change his personality by imposing upon him what he doesn’t have the power t change (literally).
The up-cycled fabric washed a dozen times (and possibly more), naturally gives them a memory and soft shape unplanned.