The human arm has a shoulder, an elbow, and a wrist, and it is used for a wide range of activities, including grasping, reaching, and throwing. The bird's wing has a shoulder, an elbow, and a wrist, but it is specialized for flight. The bones of the wing are hollow and lightweight, and the wing is covered in feathers. The wing also has a number of muscles that allow the bird to control its flight.
The similarities and differences between the human arm and the bird's wing are a result of evolution. Both structures evolved from a common ancestor, but they have evolved different adaptations in response to different environmental pressures.