bullet train vs passenger train

bullet train and passenger train both are nouns.

Word	Noun	Adjective	Verb	Adverb
bullet train	Yes	No	No	No
passenger train	Yes	No	No	No

As nouns, passenger train is a hypernym of bullet train; that is, passenger train is a word with a broader meaning than bullet train:

bullet train (noun)	passenger train (noun)
a high-speed passenger train	a train that carries passengers