The condensate from a dehumidifier is unlike a water distillation unit.
In the dehumidifier ambient air is forced across refrigerated fins, causing the high humidity air to condense on the cold surface, but it is an open Link system that is also drawing air pollutants, dust, mites, whatever nasties are also present in the humid air. When the water condenses in that system it also takes with it all those "nasties".
A water distillation system (for human consumption) is a closed link2 system herein water is boiled (by a combination of heat and vacuum) to create saturated steam. That saturated steam is then condensed.
The other difference is that the dehumidifier relies on ambient air as the source, while the water distillation (for drinking purposes) relies on water as the distilland, that is flushed out as it becomes progressively more concentrated with minerals, salts, etc.
Commercial distillation systems (for human consumption) are nevertheless cleaned and disinfected, unlike your dehumidifier.