neonatal mortality rate vs neonatal mortality

neonatal mortality rate and neonatal mortality both are nouns.

Word	Noun	Adjective	Verb	Adverb
neonatal mortality rate	Yes	No	No	No
neonatal mortality	Yes	No	No	No

As nouns, neonatal mortality rate and neonatal mortality are synonyms defined as:

neonatal mortality rate and neonatal mortality: the death rate during the first 28 days of life

neonatal mortality rate (noun)	neonatal mortality (noun)
the death rate during the first 28 days of life	the death rate during the first 28 days of life