Based on the Sai Satcharitra, what is the difference between a knowledgeable teacher and a true Sadguru?

Chapter 48 of the Sai Satcharitra draws a clear distinction between a teacher with mere scriptural knowledge and a true Sadguru. The text explains that those who simply study the Vedas, explain Vedanta, or perform practices like Pranayama are not necessarily Sadgurus. The defining characteristic of a Sadguru is the possession of direct, full self-experience, not just vast verbal knowledge which is described as 'verbally hollow.' As Chapter 48 clarifies, a Sadguru is one who can give this direct experience to a disciple, possessing the authority to enlighten them, whereas someone without personal experience has nothing substantial to offer.