Light dependent resistor is made of semi conductor material, and the conductance changs with light. According to this characteristic, LDR photoresistors can be produced with different figures and illuminated areas. LDR photoresistor, which is also called LDR photocell or photocell sensor, is widely used in many industries, such as toys, lamps, camera, etc.
The light sensor is a device which converts light energy of various wavelengths from infrared to UV into the electrical energy(or to an electrical signal). This is the reason why they are named as photoelectric devices. They sense the light during this process, and so can be called as 'photo sensors'.
The light sensor is a passive devices that convert this "light energy" whether visible or in the infra-red parts of the spectrum into an electrical signal output. Light sensors are more commonly known as "Photoelectric Devices" or "Photo Sensors" because the convert light energy (photons) into electricity (electrons).