The Blu-Ray discs have almost 2-1/2 times the resolution of the DVDs, which means a sharper picture. A simple look at screencaps will show a sharper picture and more vibrant colors. It IS a matter of technical fact. The Blu-Rays are a SIGNIFICANT improvement in picture quality over the DVDs, sourced from freaking VHS tape!
One look at any of the comparison videos that are out there and you can clearly see the difference in sharpness, quality, and colors. This is no slight improvement. It's night and day.
But, hey, the special effects team for Season-2 made a sliver of a viewscreen clip into the wall, so.