growth rate vs rate

growth rate and rate both are nouns.

Word	Noun	Adjective	Verb	Adverb
growth rate	Yes	No	No	No
rate	Yes	No	Yes	No

As nouns, rate is a hypernym of growth rate; that is, rate is a word with a broader meaning than growth rate:

growth rate (noun)	rate (noun)
the rate of increase in size per unit time	the relative speed of progress or change
	amount of a charge or payment relative to some basis
	a quantity or amount or measure considered as a proportion of another quantity or amount or measure
	a magnitude or frequency relative to a time unit

growth rate (verb)	rate (verb)
	assign a rank or rating to
	estimate the value of
	be worthy of or have a certain rating