streetcar vs trolley car

streetcar and trolley car both are nouns.

Word	Noun	Adjective	Verb	Adverb
streetcar	Yes	No	No	No
trolley car	Yes	No	No	No

As nouns, streetcar and trolley car are synonyms defined as:

streetcar and trolley car: a wheeled vehicle that runs on rails and is propelled by electricity

Other synonyms of streetcar include tram, tramcar, trolley.

streetcar (noun)	trolley car (noun)
a wheeled vehicle that runs on rails and is propelled by electricity	a wheeled vehicle that runs on rails and is propelled by electricity