Size

• There is a slight size difference, although it might not be noticeable to the naked eye. First-generation models are 4.3 inches tall, 2.4 inches wide and .31 inches deep. Second-generation models are 4.3 inches tall, 2.4 inches wide and .33 inches deep.
  
  

Weight

• First-generation models weigh 4.2 oz. and second-generation models weigh 4.05 oz.
  
  

Battery Life

• The second-generation iPod Touch has more battery life than its predecessor, particularly in terms of music. The second-generation will play up to 36 hours of music or six hours of video compared with the first-generation's limits of 22 hours of music and five hours of video.
  
  

Bluetooth

• With a software upgrade, the second-generation iPod Touch is Bluetooth-compatible, whereas the first generation is not. This feature allows users to use wireless Bluetooth stereo headphones and transfer data with other Bluetooth-enabled devices.
  
  

Speaker

• For the second-generation iPod Touch, Apple included a small external speaker on the front of the unit, something that was not available on the first generation.