armed forces vs rank and file

armed forces and rank and file both are nouns.

Word	Noun	Adjective	Verb	Adverb
armed forces	Yes	No	No	No
rank and file	Yes	No	No	No

armed forces (noun)	rank and file (noun)
the military forces of a nation	the ordinary members of an organization (such as the enlisted soldiers of an army)
	people who constitute the main body of any group