From the Ask Tom mailbag:

Question:
What’s the difference between a supervisor and a manager? And why does there have to be one Stratum difference?

Response:
Elliott Jaques is one of the few researchers who recognized the power and the necessity of the “first line manager” or the supervisor. Companies who give this role short shrift do so at their peril. For a complete discussion, I will yield to Herb Klopowitz, posting for the GO Society.