I PRISONER OF WAR is a detained person as defined in Articles 4 and 5 of the Geneva Convention Relative to the Treatment of Prisoners of War of August 12, 1949. In particular, one who, while engaged in combat under orders of his or her government, is captured by the armed forces of the enemy.
“Enemy combatant” is a general category that subsumes two sub-categories: lawful and unlawful combatants. See Quirin, 317 U.S. at 37-38. Lawful combatants receive prisoner of war (POW) status and the protections of the Third Geneva Convention. Unlawful combatants do not receive POW status and do not receive the full protections of the Third Geneva Convention.
The President has determined that al Qaida members are unlawful combatants because (among other reasons) they are members of a non-state actor terrorist group that does not receive the protections of the Third Geneva Convention. He additionally determined that the Taliban detainees are unlawful combatants because they do not satisfy the criteria for POW status set out in Article 4 of the Third Geneva Convention.