horsecar vs trolley car

horsecar and trolley car both are nouns.

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

As nouns, trolley car is a hypernym of horsecar; that is, trolley car is a word with a broader meaning than horsecar:

horsecar: an early form of streetcar that was drawn by horses
trolley car: a wheeled vehicle that runs on rails and is propelled by electricity

Other hypernyms of horsecar include streetcar, tram, tramcar, trolley.

horsecar (noun)	trolley car (noun)
an early form of streetcar that was drawn by horses	a wheeled vehicle that runs on rails and is propelled by electricity