Much of Sun Tzu's Science of Strategy revolves around specific definitions for its terms. Like Euclid's Geometry, much of Sun Tzu's The Art of War is devoted to definition his concepts. The book itself is designed starting at the simplest and more general concepts and working toward the most complex and specific.
For those who like a simple dictionary, you can see the definitions from Sun Tzu's work here. However, this "dictionary" approach of concepts doesn't capture the Sun Tzu's concepts well because all of his concepts are defined in their relationships with other concepts. Diagrams showing these relationships work well, and we offer a number of such diagrams in our various articles and training sessions.
Sun Tzu, of course, didn't use English terms. We adapt existing English concepts to his concepts as well as we can, even when they fit poorly. Though we talk about Sun Tzu's "strategy," his idea of competitive methods (bing-fa) was much narrower than many ideas of strategy.
Many people see strategy as a high-level, long-term plan. Sun Tzu's bing-fa was, to a large degree, a reaction against this view. His definition was much closer to the definition of strategy used in modern game theory: a chosen set of methods reacting to possible situations. These methods set are chosen with a big-picture view of mission and the competitive environment. Because of this, some might call Sun Tzu's work a book of tactics.
Unlike those who claim to be able to offer an absolute definition separating strategy and tactics, Sun Tzu's defined his concepts in the context of each other. His "strategy" was a specific method for choosing the right action from among a group of potential tactics. A tactic was the chosen response to a situation, that is, the execution of the response. Why that particular tactic is chosen depends upon the entire strategy, but the way that response is executed depends on the tactics.
For example, a general rule of Sun Tzu's strategy is to avoid conflict. Most of his methods are designed to develop superior positions without engaging in the destructive behavior of wars of attrition. Most of his tactical responses are chosen to discourage others from attacking us in different situations because the overall strategoc system itself is based on avoiding conflict. However, when conflict is unavoidable, his strategy also includes a number of methods, that is, tactics, for succeeding under the conditions of conflict. Why do these methods exist within a system that avoids conflict? Because an even larger part of Sun Tzu's system is the rule that we cannot completely control the course of events. Things in copetitive happen that we do want and cannot avoid and we must react.
In our list of standard terms, we define a strategy as "a set of rules for making decisions about whatever situation might arise." We define tactics as "the chosen response to a given situation. The process of making the decision about a given situation is the whole of our strategy. The execution of the chosen response is the whole of our tactics.