In today's world, we believe that it's not hard to diagnose our illnesses and issues. After all, the modern human being has access to all of the knowledge in the world. The World Wide Web at our fingertips, as well as thousands of books, magazine articles, and "expert" friends whose expertise derives from too many health-craze TV shows, it's easy enough to believe that we can tell the difference between the stomach flu and a headache. However, not all illnesses are so easy to identify and distinguish. What about allergies and sinus infections? They share almost all of their symptoms--so those websites, articles, and friends might mislead you. What is the real difference between allergies and sinus infections?