military rank vs rating

military rank and rating both are nouns.

Word	Noun	Adjective	Verb	Adverb
military rank	Yes	No	No	No
rating	Yes	No	No	No

As nouns, military rank and rating are synonyms defined as:

Other synonyms of military rank include military rating, paygrade.

military rank (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