Aside from the lower resolution, differences include fewer phase-detection autofocus points (273 compared to 493) and an added anti-aliasing filter.
The F-to-Z mount adapter accessory allows for using Nikon lenses from the digital SLR series with full compatibility.
The only negative comment at that time was that the Z6 offers only a single XQD card slot; such cards were still quite expensive at the time and a single slot does not provide any "backup security".
[8] Digital Photography Review rated the camera's sensor as providing excellent resolution and high ISO performance, "though on rare occasions you may see banding if shadow areas are brightened ...
Low light Raw performance is competitive with the best of its peers, which is to say it's essentially class-leading.
"While the Nikon Z7 may garner the most attention, the cheaper Z6 may actually prove the more impactful of the two cameras, since it'll be within reach of a larger number of photographers.
The Z6 and Z7 have - so far - always received largely identical changes and share the same firmware version numbers.