I think it depends on where you live. on the Wii, 576i is 50Hz mode, 480i is 60Hz mode and 480p is progressive scan mode. NTSC and PAL video are different. Well why does 1080p seem so much clearer than 480i?
Of course there is a difference. A big difference. Has anybody actually seen 1080p video compared to 480i? There is a difference in quality and it is very noticable.
The Wii does get bad ports. Sonic Unleashed on Wii/PS2 is quite different from the 360/PS3 version. Although that isn't a port it is still a bad version. At least the Wii version has better graphics than the PS2 version.