I've often wondered the same thing but maybe not in the same way. I wonder if people see the same colors and hear the same sounds, etc. For example while you are growing up, you are taught that a certain color corresponds to blue and another corresponds to yellow, and so forth. Growing up, there are never any discrepancies. If you and I were asked to identify the color of the same object, we would both identify that object as being blue, or being yellow. BUT, are we really seeing the same color? we have the same word, but do we have the same image in our brain? if I traded eyes with you, would I start identifying blue as purple?