death seat vs car seat

death seat and car seat both are nouns.

Word	Noun	Adjective	Verb	Adverb
death seat	Yes	No	No	No
car seat	Yes	No	No	No

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

death seat: the car seat beside the driver of an automobile; believed to be the most dangerous place to sit in a car in case of an accident
car seat: a seat in a car

death seat (noun)	car seat (noun)
the car seat beside the driver of an automobile; believed to be the most dangerous place to sit in a car in case of an accident	a seat in a car