military operation vs military

military operation and military both are nouns.

Word	Noun	Adjective	Verb	Adverb
military operation	Yes	No	No	No
military	Yes	Yes	No	No

military operation (noun)	military (noun)
activity by a military or naval force (as a maneuver or campaign)	the military forces of a nation

military operation (adjective)	military (adjective)
	associated with or performed by members of the armed services as contrasted with civilians
	characteristic of or associated with soldiers or the military
	of or relating to the study of the principles of warfare