Other terms to distinguish between is, 'thatch' and 'dead grass' or what I call 'mulch'.
But the real question is: How do you decide if a customer needs your power rake/dethatching service???
We take out a sample of hte soil and look at it. If they have 1 inch or less of thatch we do a power raking, its when they have greater than 1" of thatch its a dethatching. Even then we do not go deep. More of a deep power raking, becasue honestly dethatching is extremely bad for the lawn. Its expensive. We are charging $28.00 per k for dethatching, plus then seed and starter fert after that. Most lawns are in the 8k range here, so thats $224.00 for dethatching, then $300 for powerseeding and starter fertilizer