An ``X terminal'' is almost a stand-alone computer by itself, with an internal processor and a few megabytes of memory. The processor displays windows and handles mouse and keyboard input locally, relieving a compute server from doing these low-level tasks. An X terminal rarely, if ever, runs an application itself, though; instead it just draws windows and menus and handles the user interface for applications running on other machines. The name comes from the X window system, a common protocol used by window-based applications (Section 2.3).
Workstations are single-user computer systems. They range in complexity from simple personal computers to advanced processors with sophisticated graphics and vector processing capabilities. Their common attributes include the fact that they can operate as stand-alone computer systems and usually have a ``point-and-click'' (window-based) user interface. Most often the person using a workstation will sit at the console and use the main keyboard and mouse. Unix workstations allow several users to log in to the system. In a networked environment it is not uncommon for additional users to log in by sitting at a terminal and using the communication server to connect their terminal to the workstation.