In de goldmemberlinkdump wordt verwezen naar een linkje met wat meer tekst en uitleg:

[T]he waterboard technique ... was different from the technique described in the DoJ opinion and used in the SERE training. The difference was the manner in which the detainee's breathing was obstructed. At the SERE school and in the DoJ opinion, the subject's airflow is disrupted by the firm application of a damp cloth over the air passages; the interrogator applies a small amount of water to the cloth in a controlled manner. By contrast, the Agency Interrogator ... applied large volumes of water to a cloth that covered the detainee's mouth and nose. One of the psychologists/interrogators acknowledged that the Agency's use of the technique is different from that used in SERE training because it is "for real--and is more poignant and convincing."

Zoals ik het opvat: het verschil is 'de hoeveelheid water in een koffiekopje' vs. 'een emmer water'.