Hi AOB, click on the topmost photo and then use the directional arrows to quickly shift between each image. Your brain is wired to spot sudden change, so this should help you see the differences between the images. There are a lot of improvements across the entire image, including the colours too. It's night and day for me, but I do have an instinctive penchant for high visual acuity.
I have very fickle eyes and need my visuals to be tack sharp, so I have been using Reshade to improve image quality in Aerofly FS2. It's only available on Nvidia GPUs. This tool is a kind of injector which allows you to add a variety of different shaders to add visual effects, such as sharpening, colour changes, HDR, etc.
I have attached some "before and after" images showing a crop from my screen before (no reshade active) and after (reshade activated with a variety of shaders). I am running the sim at max settings, 2560 x 1440.
Reshade can be found here: Reshade.
Aha! I have established that I can clear this issue by logging out and then logging back in again. All sorted.
I have just joined and also have this issue. I'll wait a while and see if it clears up.