Well done; How a low light and low key photo technically differ?
Right. So as it was taught to me, low key images can be one or both of two things. As per the histogram a hard left shift. and/or, and, a generally, low light image that has a feeling of despair, sadness, loneliness, etc.
With this particular images, I went with the former definition.
Nicely captured.
Well, whatever your goal is for this shot, I think you have achieved both. I kinda like the sad desolate purpose of your trial. I am more emotional I suppose...Good job!
The definition I was taught was that a low key image is a properly exposed image that predominantly dark colours exposed on a dark background. A properly exposed image shows a full tonal range, but as Erik says the histogram is heavily shifted to the left, but there are limited highlights as well.
The other definition I was taught was that a B&W image shows a full tonal range from pure black to pure white.
When I pull this image into Photoshop, it does not quite pass these tests as it looks to be at least a full stop underexposed. The highest "light" value I get is around 180 while I would expect to get a value of close to 255.