Difference Between a Machine and a Structure

The following differences between a machine and a structure are important from the subject point of view :
1. The parts of a machine move relative to one another, whereas the members of a structure do not move relative to one another.
2. A machine transforms the available energy into some useful work, whereas in a structure no energy is transformed into useful work.
3. The links of a machine may transmit both power and motion, while the members of a
structure transmit forces only.