SCADA (supervisory control and data acquisition) and HMI (human-machine interface) are related but distinct concepts. SCADA is a type of system used to monitor and control industrial processes, while HMI is a graphical interface within a SCADA system that allows operators to interact with and monitor the process. In other words, HMI is a component of a SCADA system. SCADA software may run in an HMI.
SCADA systems typically include a variety of components, including sensors, control devices, communication networks and software for data acquisition (DAQ), analysis and reporting.