The Spylux has a design flaw when twilight sensor - they like to turn off again as soon as they sensed their "own light"; it can even lead to a "flashing effect" come (every few seconds-from-an). The Nightlux is rectified here that goes on and stays on, even if they are held under a spotlight. That ignores the brightness sensor as soon as it has been turned on once!
The three LEDs of Spylux goals all in the same direction, while the three of Nightlux are arranged slightly offset. The illumination is thus better (wider)!
When Spylux there is only "on", "off" and "auto", the Nightlux has in automatic mode, a 10- and a 60-second choice. The slide switch for this is in the Nightlux in the battery compartment, at the Spylux he is outside.
I therefore recommend the Nightlux.