First and Second Generation iPod Nano

The first-generation iPod nano came in three models—1 GB, 2 GB, and 4 GB—
and two colors: white with a grey Click Wheel and black.
The first-generation iPod nano incorporates the same style Click Wheel as the
previous iPod mini models. On the bottom of the unit, you find the docking
port plus the audio jack . Not everyone is happy with Apple
for putting the audio jack on the bottom, because it isn’t the most convenient
place for a headphone connection, although it makes better sense for certain
kinds of carrying cases and accessories.
The first-generation iPod nano discontinued iPod’s four-year tradition of
FireWire support. USB is now the sole method of connecting the iPod nano to
other devices. You can charge your nano’s battery via FireWire, but you get a
pop-up window that informs you that you can’t make a data connection.

The second generation iPod Nano

The second-generation iPod nano appeared in September 2006 in a spectrum of
colors and storage capacities. The 2-GB model came in silver; the 4-GB model
came in silver, green, blue, pink, and red; and the 8-GB model came in black and
red.
Like the first-generation iPod nano, the docking port and audio jack are both
on the bottom of the unit , and USB 2.0 is the sole method
of connection.