Have a new Bosch 800 series dishwasher. Interesting that the Heavy cycle takes less time to complete than the Auto cycle. Dose the Heavy cycle use more water or use both wash arms instead of 1 at a time?
On some models the "heavy" or "power" cycle will run the wash motor at faster speed for greater water pressure. On the opposite end, delicate will power the motor down for less pressure.
Consumers are more likely to choose a cycle that "does the thinking for them" so the often-used Auto cycle is made to be more frugal with water and energy... but not time. And yes, Heavy uses more water and heat so it can get the job done faster. The actual consumption data should be in the manual.