Bhai hydraulic power steering (HPS) works by the help of oil pump driven by engine....pump makes oil pressure in steering rack so when one turn the steering,pressure goes with it making turn easy. But HPS uses mechanical power of engine to work decreasing engine efficiency.
Electronic power steering (EPS) had an torque sensor + motor fixed in steering column connected with manual steering rack. Now when one move the steering, computer of EPS gets signal from torque sensor and send it to motor which moves steering with you to lower the force required to move in actual. EPS is newer technology and much better then HPS and also increase and decrease the force require to move the steering depending upon speed. MUCH safer then HPS.