It may be a British use of the word but the advice is to cook in a coffee percolator and they illustrate a drip brewer. These are two different appliances to my knowledge. A coffee percolator is a pot of water with a tube in the center which directs hot water up and over the coffee. The water essentially cycles as long as you keep boiling it.

A drip brewer cycles the water once. I can see that being better for rinsing away impurities but also requiring quite a bit more water.