Dream in here is a dream while sleeping. A dream is something that is close to the us. And everyone in the world would have ever dreamed or even non-human animals, it is still a dream.
This is a dream in a dream while sleeping. The dream is close to us. And everyone in the world had ever dreamed. Or, even a non-human animal, but it is still a dream.
Dream in here is the dream while sleeping. The dream is very close to us, and everyone in the world would ever dream. Or even animals that do not use the human's dream.