baggage car vs railroad car

baggage car and railroad car both are nouns.

Word	Noun	Adjective	Verb	Adverb
baggage car	Yes	No	No	No
railroad car	Yes	No	No	No

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

Other hypernyms of baggage car include car, railcar, railway car.

baggage car (noun)	railroad car (noun)
a railway car where passengers' bags are carried	a wheeled vehicle adapted to the rails of railroad