There is a difference between reacting and responding. Let me explain.
A reaction is control by emotion. No more, no less. Whether that emotion is fear, anger, lust, or love. For example, if I were to take a swing at you, you wouldn't stop and think about what to do. You would run, throw your hands up, or start swinging back. The fear of being hit dictates your actions.
A response is controlled by conscince thought. You actually think about how you are going to handle the situation at hand.
An example would be if I throw a frisbee at you. You can decide, to catch it, run after it, let it hit the ground, or not do aything at all. The point is, you counsciously thought about your actions before you acted them out.
Just something to think about when you are faced with a situation where a reaction or a response could make a very big difference in how the situation plays out and ends.