How is declaring war differ from military action

I think declaring war means your letting the enemy know of war and military action is when the military deals with a situation

Explanation:

War = large scale conflict between two armies.

A military operation = anything involving the military, including maneuvers, fighting, disaster relief etc.

The def. of "war" isn't strictly defined. There is a necessity of it being big in magnitude/duration/scale compared to individual battles.

it is a better alternative