The #3 difference is my TV settings. They're all wacky in Skyrim, I've got the color cranked up so high, if I watched normal television with these settings the color would be bleeding everywhere!
Matter of fact, I'll just post my Oblivion TV settings versus my Skyrim TV settings. Keep in mind that "63" is the max setting.
Oblivion Brightness: 40/63
Color: 18 or 19 out of 63
Picture: 55 to 63
SkyrimBrightness: 47/63
Color:
30 to 35Picture: 55 to 63