photocell vs sensor

photocell and sensor both are nouns.

Word	Noun	Adjective	Verb	Adverb
photocell	Yes	No	No	No
sensor	Yes	No	No	No

As nouns, sensor is a hypernym of photocell; that is, sensor is a word with a broader meaning than photocell:

photocell: a transducer used to detect and measure light and other radiations
sensor: any device that receives a signal or stimulus (as heat or pressure or light or motion etc.) and responds to it in a distinctive manner

Other hypernyms of photocell include detector, sensing element, transducer.

photocell (noun)	sensor (noun)
a transducer used to detect and measure light and other radiations	any device that receives a signal or stimulus (as heat or pressure or light or motion etc.) and responds to it in a distinctive manner