It might be because your dreams are frequently wish-fulfillment fantasies, which are very vivid since they contain things you really, truly want. Dreams, for many of us, are more vivid than actual life because they come from the head rather than the emotions. Nightmares, on the other hand, can be quite terrifying because they come from the emotions rather than the mind. Your dreams are also likely different from reality because we only remember the positive aspects of our lives. Therefore, we tend to forget the bad times completely or only remember them in a negative way. This is why we sometimes have nightmares about something that hasn't happened yet. It's also why we dream about unpleasant things: so that we can deal with them later. And finally, the reason why your dreams seem more real than life is that your brain doesn't register any difference between dreams and reality. Both are just patterns of electrical activity in the brain. So if you think about it, everything that happens to you in your dreams must be exactly what happens to you in reality too!