A HMI (Human Machine Interface) is just like a SCADA a monitoring device which displays the status of the machine. The main difference is that SCADA is a remote monitoring system, where as HMI is local to machine.
Example: Human Machine Interface vs SCADA
A HMI for example, would be placed on the control panel near a part of a machine, where as SCADA would be set up in a control room, far away from the machine itself.