prisoner of war vs POW

prisoner of war and POW both are nouns.

Word	Noun	Adjective	Verb	Adverb
prisoner of war	Yes	No	No	No
POW	Yes	No	No	No

As nouns, prisoner of war and POW are synonyms defined as:

prisoner of war and POW: a person who surrenders to (or is taken by) the enemy in time of war

prisoner of war (noun)	POW (noun)
a person who surrenders to (or is taken by) the enemy in time of war	a person who surrenders to (or is taken by) the enemy in time of war