Nano VS. Mini
The currently shipping iPod nano replaces the iPod mini. Both models use the "Clickwheel" (which places pressure sensitive navigation buttons underneath the scroll wheel) introduced with the iPod mini, but the similarities between the iPod mini and iPod nano end with the "Clickwheel".
The iPod mini shipped in a colorful "ultra-portable (3.6 inch tall, 2.0 inch wide, 0.5 inch thick) lightweight anodized aluminum" case available in five stylish colors--silver, gold, pink, blue and green (four colors from February 23, 2005 to September 7, 2005 with gold no longer offered), each with a 1.67-inch "white backlit" monochrome LCD display. The iPod mini has either 4.0 GB or 6.0 GB hard drives to hold approximately 1,000 or 1,500 songs (encoded at 128-bit), respectively.
The iPod nano, on the other hand, ships in a "impossibly small" 3.5 inch tall, 1.6 inch wide, and 0.27 inch thick "iBook white" or jet black and stainless steel case with a 1.5-inch "blue white backlit" 16-bit color LCD display. The iPod nano has either 2.0 GB or 4.0 GB of solid state Flash Memory and can hold approximately 500 or 1000 songs, respectively, in 128-Kbps AAC format and up to 25,000 "iPod nano-viewable" photographs