A robotic arm is a type of mechanical arm, usually programmable, with similar functions to a human arm; the arm may be the sum total of the mechanism or may be part of a more complex robot.
The links of such a manipulator are connected by joints allowing either rotational motion
There are two generalized schools of thought when it comes to robot hand design. You have robot hands that are simple and straightforward and get the job done, like two- or three-finger grippers that can reliably do many (if not most) things well without any fuss.