Can you elaborate on the distinction the Satcharita preface makes between worldly service and spiritual service?

Chapter 0 of the preface makes a clear distinction between different forms of service. Worldly service, such as writing biographies of great politicians or jurists, is acknowledged as a form of public and Guru service. However, its fruit is not eternal because it is limited by space and time and is often rooted in self-interest, thus not yielding spiritual benefits. In contrast, writing the biographies of saints is considered a form of spiritual service that yields spiritual fruits. Yet, the text cautions that even this is a one-sided or partial service, and it is impossible to attain the ultimate spiritual goal through such an act alone.