War: the fighting between the main forces of both sides or the main forces of the theater is generally for political purposes.

Campaign: the sum total of a series of battles carried out by the campaign corps in accordance with a unified operational plan in a certain space and time in order to achieve the partial or overall strategic objectives of the war.

Combat: Organized armed conflict, in which opposing sides put in troops from division to squadron.

2. Different parts of speech

War and battle can only be nouns, and fighting can be both nouns and verbs.

In the flood fighting and emergency rescue, the PLA and the people fought side by side and forged deep feelings. (verb)

He played a war hero in the film, and his performance was natural and realistic, which left a deep impression on me. (noun)

3. Different scales

The war is the largest and can cover the whole world, such as the First World War.

The scale of the campaign is generally local, such as the Huaihai Campaign.

The scale of combat is the smallest, and it is generally a small level.