Apparently the Xbox 360 installed version of the latest Bethesda Elder Scrolls title looks worse than the non-installed version with worse textures and more. However by installing the Skyrim DVD on to your console hard drive can make load times quicker and mean your console will make less loud loading noises which can be very annoying.
Judge for yourself in the screenshots below.
Click on image to enlarge.
As you can see their isn’t much difference between the screenshots so not installing the game to improve visuals is not really worth it. The only screenshot where the image looks noticeably different is in the first two of the Jarl. On those screenshots you can see the walls look more blurry when the game is installed. Whether this happens on the PlayStation version I’m not sure.
By installing the game the visuals look a little worse but quicker loading times and less noise more than makes up for it.