Zelda: Twilight Princess and Skyward Sword possess very different art styles. Whereas Twilight Princess is rather dark and brown to fit the atmosphere, you could say that Skyward Sword is much more colorful.
One passionate fan has come up with an intriguing mix of the two games. GBAtemp member “disbala” is working on a Twilight Princess texture pack (requires Dolphin) that incorporates the style of Skyward Sword.
While not complete, you can already see how noticeably different Twilight Princess looks with Skyward Sword’s style. You can find a few example shots above.
Thanks to Yono for the tip.