Critical thinking is the broader term. It can include strategic thinking, but it can also include other forms of “non-strategic” analysis such as the criticism of plans.
Strategic thinking, when we use the term accurately, is much narrower, focusing specifically on the world of competition. By definition, a “strategy” is a choice of actions in an environment where others, often called “agents,” are going to react to your actions. In a strategic contest in human society, people can choose to support your actions, oppose your actions, or ignore your actions. You must choose strategic actions based upon the reactions you expect from others. Strategy must deal with human psychology, which is less predictable in fundamental ways than inanimate objects.
Critical thinking about actions that act on inanimate objects are much simpler, depending on an accurate analysis of the nature of the objects. Objects do not “choose” a reaction. Glass shatters. Water flows. Light reflects and so on. Many of these reactions are deterministic. Others are probabilistic. However, all can be critiqued based upon how well the object is understood. And many objects can be understood very well. Their potential reactions to our actions are predictable because they are strictly limited by nature. Planning works will when workong on inanimate objects because of their predictability.
This stands in stark contrast to understanding people. Individuals are never well understood, not even by themselves. Nor are they predictable. Humans has the ability to invent new reactions in response to new situations. In competitive enviornments, plans collide producing situations that no one planned. Strategic thinking is guided by certain rules, but none of these rules are a prediction about what must happen.
The only certain rule in strategic thinking is that we must always “plan” to adapt our actions to new developments.