military vs United States Army

military and United States Army both are nouns.

Word	Noun	Adjective	Verb	Adverb
military	Yes	Yes	No	No
United States Army	Yes	No	No	No

military (noun)	United States Army (noun)
the military forces of a nation	the army of the United States of America; the agency that organizes and trains soldiers for land warfare

military (adjective)	United States Army (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