What are the differences between the second generation iPod nano models?

Please note that all iPod models mentioned in this Q&A have been discontinued. The second generation iPod nano was replaced by the third generation iPod nano on October 13, 2006.

All of the second generation iPod nano models share sleek 3.5 inch tall by 1.6 inch wide by 0.26 inch deep aluminium cases similar in style to the discontinued iPod mini (2nd Generation) players.

Photo Credit: Apple Computer

Each second generation iPod nano shares a modest number of new features -- perhaps most notably a promoted 24-hour battery life for music playback (five hours for slideshows with music), a brighter display, gapless playback (in concert with iTunes 7, so songs that are supposed to "fade into" one another will do so rather than having a seconds long break between them), and a search engine to make it easier to find a particular song.

The second generation iPod nano models, like the original iPod nano, support a number of audio and photo formats, but do not natively support video playback.

Differences between models are modest, and can be summarized by capacity, color, and price. For your convenience, the variations are summarized in this handy chart:

Also see: What is the difference between the red iPod nano and the standard second generation iPod nano?