i would imagine tactics and strategy to be the same definition.
Tactics is reaction to situation, in war situation tactics are movements (and other actions) to counter enemy movements, logistics movements (supply lines), etc.
Strategy is fore planning, the decision to attack using the rear route, pincer movement, ambush, cut supply lines at a specific point, etc.
The decision to land at Omaha beach (WWII D-day) was strategy. Note I said "the decision," because once there, the landing itself is tactics. The precise movements of troops on the beach once they are there are tactics.
Another example, Rommel's tank brigade is spotted, and direction of movement is known. The decision to attack or ambush him at a certain point, from given angles or approach routes, is strategy. Once the attack begins, when the attacking units are in their proper positions, ready to either advance to battle as planned or wait in ambush, it is all tactics. Too many games set up the strategy before your map is loaded, leaving you with nothing but tactics. I feel more of a sense of gratitude, accomplishment, if it were my strategy that helped precipitate a victory.