Aux heating coolant diesel is the factory fitted optional upgrade to the standard coolant heater, which without the upgrade can not be controlled by the driver. The standard one comes on below 5 degrees to lower emissions by helping the engine to reach operating temperature. With the optional factory upgrade, it can be turned on manually, or programed to come on at a chosen time, so that you can preheat the motor on cold mornings to lower wear on the engine during warm up. It also preheats the cabin through the dash outlets. Because it runs fans and coolant pumps, it has high battery usage, and is not intended to be used as a cabin heater through the night. Until 2018 this preheater factory upgrade ran off the leisure battery, from 2019 on it runs off the starter battery. Because in the UK this option was not available on the Ocean, some Ocean owners have fitted a Polish made controller to the standard coolant heater, and therefor this aftermarket setup runs off the starter battery.
The Night heater, which also burns diesel but runs off the leisure battery and is designed to have low battery usage, is meant to heat the cabin air with the engine off. Its outlet is at the bottom of the B pillar, at the FRONT of the sliding door opening. It's a separate machine, fitted under the right side of the vehicle, while the coolant preheater is under the left side. These are two different machines with different purposes.
There is another confusingly named rear auxiliary heater, an optional extra available only on the semi-manual Climatic system (the fully automatic Climatronic 3 zone climate control has different ways of heating the rear seating area). This is an add on heat exchanger and rear outlet near the bottom of the C pillar at the BACK of the sliding door opening, and is an extension of the normal car heater.
Finally, there is the "Rest" control on the climate control panel of Climatronic. This uses residual engine coolant heat to warm the cabin for about 1/2 hour after the engine is turned off.
As above, the only electric heating available is if you plug in an electric heater while you are on Electrical Hookup.
And, as you have experienced, the VW descriptions of these different options look like they were written by the proverbial random bashings of a monkey on a typewriter.