stoplight vs traffic light

stoplight and traffic light both are nouns.

Word	Noun	Adjective	Verb	Adverb
stoplight	Yes	No	No	No
traffic light	Yes	No	No	No

As nouns, stoplight and traffic light are synonyms defined as:

stoplight and traffic light: a visual signal to control the flow of traffic at intersections

Other synonyms of stoplight include traffic signal.

stoplight (noun)	traffic light (noun)
a visual signal to control the flow of traffic at intersections	a visual signal to control the flow of traffic at intersections
a red light on the rear of a motor vehicle that signals when the brakes are applied to slow or stop