Differentiate PLC & SCADA?

PLC is a programmable logic controller is a small, modular solid state computer with customized instructions for performing a particular task. PLCs, which are used in industrial control systems

PLC is the Programmable logic controller ,which can controls the system i.e conveyor running sequence , valve operations with interlocks and permisses etc  .Unit operation control philosopy is programming  into the controller by using Software.It can control the system by using Digital signals 0 and 1 . Sensors are controlled by using Analog signals which is like 0 -24 MAMPS.These Amps  will get convert into counts to the Module , when receiving signal from the sensor. 

SCADA Supervisory control and Data Acquisition, SCADA is used to operate and monitor the unit.SCADA gets all the field input signal from PLC Modules and display it on the screen. Each Digital and Analog Module or card has unique address. SCADA can access that address  and receive the signal from Digital input card and displays it on the Screens, same vice versa for output start /stop .

The PLC is the Hardware equipment  manage the inputs/outputs signals according to agreed configuration, but SCADA is the Screens that show to the operator the status of these signals.

PLC is hardware or controller which controls the process where SCADA is monitoring and visualization software which displays the real time animation about process or machine execution.

Scada is taking signal from PLC and display on PC or HMI based on animation. 

A PLC monitores and decides the output based on the programmed input wheras SCADA acts a remote control for controlling electronic equipments

A PROGRAMMABLE LOGIC CONTROLLER (PLC) is an industrial computer control system that continuously monitors the state of input devices and makes decisions based upon a custom program to control the state of output devices where as Supervisory control and data acquisition (SCADA) is a system of software and hardware elements that allows industrial organizations to: Control industrial processes locally or at remote locations. Monitor, gather, and process real-time data.