Two ways to build a clutch
Ducati has used both kinds. Each one squeezes a stack of friction and steel plates together to pass engine power to the gearbox. The difference is whether the stack runs dry in air (left) or in engine oil (right).
How the plate stack works
Orange friction plates turn with the basket, which the crank drives. Grey steel plates turn the gearbox shaft. Pulling the lever lifts the pressure plate away from the stack, so the plates slip apart and power stops.
Dry clutch: the classic Ducati
An oil seal keeps the plates out of the engine oil, and air through the open cover cools them. That means no oil drag and sharp, direct engagement. The cost is the famous rattle, faster wear, clutch dust and a heavier lever.
Wet clutch: the modern Ducati
The plates spin in the crankcase oil, which cools them and cushions engagement. The clutch is quiet and smooth and lasts much longer, and with a slipper ramp the lever is light. The downsides are a little oil drag and a clutch that shares, and wears, the engine oil.
Why Ducati switched
Dry clutches defined the 916 family, the 1098 and 1198 superbikes and the air-cooled Monsters. Since the Panigale 1199 (2012), most Ducatis use wet slipper clutches. They are quieter for noise rules, need less upkeep and are kinder to riders in traffic.