paygrade vs rating

paygrade and rating both are nouns.

Word	Noun	Adjective	Verb	Adverb
paygrade	Yes	No	No	No
rating	Yes	No	No	No

As nouns, paygrade and rating are synonyms defined as:

Other synonyms of paygrade include military rank, military rating.

paygrade (noun)	rating (noun)
rank in a military organization	act of ascertaining or fixing the value or worth of
	an appraisal of the value of something
	standing or position on a scale
	rank in a military organization