Maybe smaller pictures that can both be seen at the same time would illustrate the difference(s) better??
Good point!
Instead of making a smaller version, I have made a gif animation that toggles between the two images::
On my monitors the difference is quite noticeable.
The darker image is the one with "ambient lighting"set @ 100%.
If you still don't see any difference, I suggest you check your monitors contrast / brightness balance. There should be a built-in calibration procedure you can follow.
Cec