Unless its the lighting, I still say the bottom 2 are different then the top 2. At least the top right seems to have a sharper contrast then the others, and a "stronger" yellow.
The bottom 2 have a softer contrast and softer yellow and a almost pinkish hue to the white.
The top left seems in shed, so not sure, but I think tends to go more towards the higher contrast?
again, no expert here![]()