Old souls are beings who have incarnated many times, through many lifetimes on this and other planets. Young souls have not incarnated as much, for a number of reasons. Even people who are not spiritually intuitive can detect a young soul. No matter what their chronological age, they seem like an empty room, with the breeze floating through. Whereas an old soul, no matter if he or she is only a baby, gives the impression of having seen it all, having experienced it all, and knowing it all too.
Many different stages of incarnation distinguish old and young souls, for each person is a unique individual. Each has karma, each soul has a journey. Some of us have a lot of karma to balance out. Some of us are at the end of what the physical experience can contribute to our soul’s growth and expansion.