The Laws and Customs of War apply to partisans and guerrilas as long as they meet the requirements. Terrorists - by their very nature cannot ever meet the requirements.
Here are the requirements to be covered under these conventions:
REGULATIONS RESPECTING THE LAWS AND CUSTOMS OF WAR ON LAND
SECTION I
ON BELLIGERENTS
CHAPTER I
The qualifications of belligerents
Article 1. The laws, rights, and duties of war apply not only to armies, but also to militia and volunteer
corps fulfilling the following conditions:
1. To be commanded by a person responsible for his subordinates;
2. To have a fixed distinctive emblem recognizable at a distance;
3. To carry arms openly; and
4. To conduct their operations in accordance with the laws and customs of war.
In countries where militia or volunteer corps constitute the army, or form part of it, they are included under the denomination "army."
Art. 2. The inhabitants of a territory which has not been occupied, who, on the approach of the enemy, spontaneously take up arms to resist the invading troops without having had time to organize themselves in accordance with Article 1, shall be regarded as belligerents if they carry arms openly and if they respect the laws and customs of war.
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