In all honesty, no, there isn't much difference. Your image for the ice challenge has more detail in the ice and a tighter crop, which I like, but I think in general, the score difference lies in that the former was entered into a free study. It seems expectations go up a few notches in the free studies, and there are so many outstanding images that it becomes much like grading on a curve.
As mentioned, the scores were both greatly affected by the challenge topic and the competition. Both excellent photos though. Even if you entered the first photo in both challenges, you would have ended up with much the same result.
I gave your ICE entry a 7 and your Free Study entry a 6, because: In the first there's more detail, the tonal range is greater, the color is less saturated and thus looking more natural. Besides that, as I commented on the first one, IMO there's too much negative space left and right - and you even extended it in the second one. Comparing the images now, I think I should have given the first an 8 and the second just a 5.
