Burned smell
If I'm not mistaken, the Asko uses a wire type heater, like most dryers, not unlike a toaster actually. These have the tendency to be more efficent in terms of heat transfer, but also more fragile and dangerous due to the actually red hot wire surface.
The Bosch has a coil heater (like the washer) with a heat sink molded onto it. This results in slightly less efficient heat transfer, but reduces the risk of lint ignition and is way less fragile, especially if some type of metal item makes it from the drum to the heater.