to tell you the truth i think both are pretty much the same. The video Ipod and the zune both have large memory, you can upload full movies-to music videos-to move clips.
The difference is...
Ipods Itunes have video available to download, zune's software doesnt for now probably because its new, but im absolutley sure that zunes marketplace will have it available some day.
zunes sceen is so much larger! its WONDERFUL for watching videos.
Zunes dont scratch like ipods. although ppl say ipods are "durable" they still get all scratched up.
Ipod comes in only 2 colors for the video ipod. Zune comes in 3. Although in pictures Zune's appearance is extremely weird looking and kind of ugly, if you go the the store and look at one up close its really nice. The double shot is actually really cool looking.
Ipods are more EVERYWHERE than zunes. Theres a LARGE amount of accessories and every store you can think of. So thats a advantage to personalize it.
Zune and ipods can both upload photos. But with the zune you can set one of your photo's as the backround which can also give you a way to personalize it.
ipod video is also much thinner and slimmer than the zune.
Zune has radio and Ipod doesn't
and finally...Zune has a wi-fi connection so if 2 people had zunes in one room you can send eachother music but can only listen to it 3 times within a 3 day period.
and thats about it! gluck on pickin!