This is really an inaccurate comparison.

Right off the bat, there's the problem that the captures were taken by two different programs. The fact that they were captured to the same file format doesn't matter, as the byte order will be different between programs.

Secondly, they were saved from BMP to JPG. I don't care how high res you save a JPG, it's a lossy format. Once again, the byte order has been rearranged.

Lastly (and most importantly), the HD image was downsampled to DVD resolution. The DVD images were upsampled to HD and then, apparently (although this isn't stated) downsampled back to DVD resolution. Two resamplings is going to destroy the detail in any image, especially when one of them is up.

A true comparison would be as they would actually appear on a screen; either HD downsampled to DVD resolution OR DVD upsampled to HD resolution. This shows neither.

Edit: I just downloaded both versions of the map image and checked the file size. The HD one is 62 KB and the DVD one is 56 KB. This tells me that both of these were saved at a lower jpg quality (my guess is around 6) and that the DVD one was probably saved after both resamplings, meaning it was sent through the jpg compression process at least twice.

Edit 2:

Good observation.

I should clarify that it wasn't a commercial HD-DVD disc, but an HD source. (LOTR hasn't been released to HD-DVD)