As the number of patients with impaired nerves is continuously increasing day by day around the globe, rehabilitation training by the physical therapist is more time-consuming and less effective. From last two decades, many robot-based upper limb rehabilitation devices have been developed for physical therapy of the human upper limb by employing state-of-the-art technologies. Hence, there is a need for a comprehensive systematic analysis to understand the basic principle and working of rehabilitation devices. The devices are primarily classified as exoskeleton- and end-effector-oriented robotic devices depending on the alignment of the upper limb joints. The objective of the review is to investigate the functionality developments of the robot-based upper limb rehabilitation devices. In this work, a systematic analysis is being carried out depending on the factors such as compatible designs, control aspects, training modes, actuation methods, and clinical developments of the devices. Furthermore, a tabular comparison is presented for the above factors considering different types of robotic devices and the status of the developments. Finally, the scope of improvement is discussed by minimizing the potential gaps between design and prototyping establishments. This review will help the therapists, researchers, and manufacturers to augment the safety and cost-effective concerns for patients with upper limb impairments.