Limbs work as levers. The systems are bound together in a unit. Scale denotes magnitude. Blowing wind varies from a baby's breath to a hurricane. Size is relative to the viewer and distance.
Structure describes the form of an object.
An object is identifiable by its shape and components, reduced to the level where it is minimally identifiable. Structures are building blocks. Objects can be identified by their shape and size through our senses. Minerals are the building blocks of the earth. Plants and animals scale and adapt their structures to their environment.