Sartan0 said:
Strategy:
1. The science or art of combining and employing the means of war in planning and directing large military movements and operations.
2. the use or an instance of using this science or art.
3. skillful use of a stratagem: The salesperson's strategy was to seem always to agree with the customer.
4. a plan, method, or series of maneuvers or stratagems for obtaining a specific goal or result: a strategy for getting ahead in the world.
Tactics:
1. The art or science of disposing military or naval forces for battle and maneuvering them in battle.
2.( used with a plural verb ) the maneuvers themselves.
3.( used with a singular verb ) any mode of procedure for gaining advantage or success.
This. And well done all the people who posted along these lines.
In terms of real-world military theory, there are three levels of warfare (obviously gaming has developed its own meanings for the following terms, but here's the actual theory). First there's the two basics
Tactics: actions on the battlefield, ranging from 'how can I move so I can shoot that one guy', up to company (120-ish men), perhaps regimental level manoeuvres. Decisions made by privates, non-commissioned officers, captains etc.
Strategy: your overall purpose in war. Where in the theatre of war do I need to position my forces? Why I am fighting this war? What are my goals? This is the stuff that the generals and, in the modern age, the politicians decide.
Round about the time of Napoleon, a third tier came in between strategy and tactics, due to the sheer size of modern armies and the scale of the battlefield available:
Operational art: the large-scale manouevre of forces such as corps, divisions and armies. Instead of small units of men flanking each other, we're talking entire armies, supported by tanks, artillery, airpower, flanking equally sized units. Its often said that where strategy and tactics are sciences, this level is an art.
In these terms, the OP is right: many real time strategy games are actually all about tactics, ie. Starcraft, Dawn of War and so on. Total War titles are a good synthesis of tactics and strategy, but they don't get the big picture very well. Grand Strategy games like Hearts of Iron and Europa Universalis are great at the high-level stuff, but not at tactics. I can't think of any game that has achieved an absolute simulation of war at all levels.
However, 'strategy' in gaming terms has come to mean something different - the ability to think logically, to know what units counter what, what buildings to construct when, what part of the map to rush for first, etc. Ultimately, we can only sort out this threat if the OP tells us which definition of 'strategy' he's talking about - the military term, or the gaming term.
Sorry about all that, I study military history at Uni. I can't help myself!