At the risk of beating a dead horse, it seems to me they could very well be the same painting. Lightsong's version has "fat strokes of the brush" while Kaladin's looks as though someone slopped the paint on with a knife. Though a knife may not leave brush strokes, kaladin is a soldier, not a painter, and could just be describing large strokes. Either way, small brushes weren't used in either painting.
More importantly is the color description. I havent seen anyone mention that the red-blue with a hint of black color described in Lightsong's painting is said to be the predominant hue, meaning there are other colors not mentioned. I would imagine white to have less of an impact on someone from Lightsong's society, who with heightening would see colors so vibrantly. White is boring compared to a whole spectrum of colors. If you add a hint of anything to it, blue for instance, it's not white anymore. You would have a very faint, light blue...not a blueish white. Pointless to describe next to complex hues of color. Regardless, the use of the word "predominant" means that without a doubt, there is something unsaid on the canvas that is not the red/blue/black (being 1 single color) he describes for us.
Kaladin sees mostly reds and whites in his. We could say that the use of the word "mostly" is the same as the use of "predominantly". The red/blue with a hint of black that Lightsong calls "a deep red, almost crimson" would just be red to kaladin's eye. If we can venture that lightsong's painting had white that he didnt care to describe due to the overshadowing of the predominant hue, we can at least say the the paintings might have the same colors.
In Oathbringer, the proprietor points out how exceptionally rare it is that a painting makes it out of the Court of Gods without being burned. What are the odds that 2 paintings with the same color scheme escaped such a nearly certain ending? What are the odds that 2 paintings with even similar colors survived? Personally, it seems quite unlikely to me. Let me go a step even further and ask what are the odds that such an extremely rare fate would befall 2 paintings of similar(if not the very same) colors by the same artist? I find that this strongly supports the same painting theory, but we of course have no way of actually knowing how often a painting lives on.
Lastly, both men are drawn to an object at the center. Its established that nenefra's paintings are famous for being interpreted as different things by different people. Kaladin and Lightsong both see a different actual shape in a sea of abstractness, but it's important that they both see it in the same location on the canvas. Right in the center.
I submit that this is evidence that these are in fact one and the same painting. I'm sure this theory has holes so poke away! First time posting so I'm expecting it.
Here are the descriptions for reference.
Kaladin:
This one was sloppy by comparison. It looked like the painter had simply taken a knife covered in paint and slopped it onto the canvas, making general shapes.
Haunting, beautiful shapes. Mostly reds and whites, but with a figure at the center, throwing out nine shadows …
Lightsong:
The canvas was thick with paint, every inch colored with large, fat strokes of the brush. The predominant hue was a deep red, almost a crimson, that Lightsong immediately knew was a red-blue mixture with a hint of black in it.
The lines of color overlapped, one atop another, almost in a progression. Kind of like . . . waves. Lightsong frowned. If he looked at it right, it looked like a sea. And could that be a ship in the center?
