death vs neonatal death

death and neonatal death both are nouns.

Word	Noun	Adjective	Verb	Adverb
death	Yes	No	No	No
neonatal death	Yes	No	No	No

As nouns, neonatal death is a hyponym of death; that is, neonatal death is a word with a more specific, narrower meaning than death:

death (noun)	neonatal death (noun)
the act of killing	death of a liveborn infant within the first 28 days of life
the event of dying or departure from life
the permanent end of all life functions in an organism or part of an organism
the absence of life or state of being dead
a final state
the time when something ends
the time at which life ends; continuing until dead