Couldnt find a good site outlining but here’s my stab at explaining…
1st Gen: Original iPod. White. Physical scroll wheel. Ring of 4 buttons surrounding scroll wheel. Firewire connection but no cover for port. Originally 5GB. Then in March 2002 added 10GB. Introduced: October 2001. Terminated: July 2002
2nd Gen: White. Wheel like trackpad. Ring of 4 buttons around wheel. Firewire connection with dock cover. 5GB. 10GB, 20GB Introduced: July 2002. Terminated: April 2003
3rd Gen: White. Trackpad Wheel. 4 buttons above wheel. Dock connection on bottom (USb and Firewire via dock). 10GB, 15GB, 30GB
Introduced: April 2003, Terminated: July 2004
iPod Mini: five metalic colors: silver, gold, pink, blue and green. Click wheel intorduced.Dock connection on bottom (USB and Firewire via dock) 4GB. Introduced: January 2004 Terminated: February 2005
4th Gen: White. Clickwheel. Dock connection on bottom (USb and Firewire via dock). 20GB, 40GB Introduced: July 2004 Terminated: June 2005
U2: Black and Red. Clickwheel. Dock connection on bottom (USb and Firewire via dock). 20GB Introduced: October 2004 Terminated: June 2005
iPod Photo: White. Clickwheel. Color screen. Dock connection on bottom (USb and Firewire via dock) 40GB, 60GB, then 40GB replaced by 30GB. Introduced: October 2004. Terminated: June 2005
Shuffle: White. No screen. USB Connection 512MB, 1GB Introduced: January 2005
Mini 2nd Gen: Every color but Gold. Clickwheel. Dock connection on bottom (USb and Firewire via dock) 4GB, 6GB. Introduced: February 2005
U2 Color: Black and Red. Color Screen. Clickwheel. Dock connection on bottom (USb and Firewire via dock). 20GB, 60GB Introduced: June 2005
iPod Color: White. Click wheel. Color screen. Dock connection on bottom (USb and Firewire via dock). 20GB, 60GB Introduced: June 2005
Nano: White and Black. Color screen. Click wheel. USB Conection. 2GB, 4GB. Introduced September 2005.
5th Gen: White and Black. Color screen. Click wheel. USB Connection. 30GB, 60GB. Video. Introduced October 2005

