iPod touch (Generation 2, 8 GB, black, 2009)

This version of the iPod touch was originally marketed as the “new iPod touch” and designated as “iPod touch (Late 2009)” by Apple. Due to its similarities, this model is sometimes confused with the Generation 3 iPod touch, but the Generation 2 model is differentiated by the fact it cannot run an iOS version beyond iOS 4.2.1.

This iPod touch was released around the same time as the iPhone 3GS and shares many features (except the iPod touch did not have 3G/EDGE phone, A-GPS, digital compass, and integrated camera).

The iPod touch Generation 2 8 GB included a multi-touch 3.5-inch display (320×480), accelerometer, ambient light sensor, and 802.11b/g/n. It used a 30-pin connector, included a stereo headphone jack, and shipped with Apple’s standard earphones of the time.

Source: Everymac, Wikipedia

iPod touch (Generation 3, 32 GB, black, 2009)

The iPod touch Generation 3 was very similar to the iPod touch Generation 2 and was released around the same time as the iPhone 3GS. This iPod touch had features similar to the iPhone 3GS, except the iPod touch did not include 3G/EDGE (phone), A-GPS, digital compass, or an integrated camera.

The 32 and 64 GB Generation 3 iPod touch models are the same externally as the Generation 2, but had 50% faster performance, OpenGL graphics, and ran up to iOS version iOS 5.1.1.

The iPod touch Generation 3 included a multi-touch 3.5-inch display (320×480), accelerometer, ambient light sensor, and 802.11b/g/n. It used a 30-pin connector, included a stereo headphone jack, VoiceOver voice control, and shipped with the same Earphones with Remote and Mic as the iPhone 3GS.

Source: Everymac, Wikipedia

iPod touch (Generation 4, 8 GB, black, 2010)

Although the iPod touch Generation 4 has a design similar to the iPhone 3GS, its features more closely resemble those of the iPhone 4 that sold at the same time. (The iPod touch lacked the iPhone 4 features of 3G/EDGE phone, A-GPS, and digital compass.)

The iPod touch Generation 4 included a 3.5-inch Retina Display (960×640 at 326 ppi), FaceTime video calling (using Apple ID), an integrated microphone and front-facing VGA camera, 3-axis gyroscope, and a 720p camera (lower quality than the iPhone 4). However, the iPod touch Generation 4 allowed iMovie editing using the iOS version of iMovie available at the time.

The iPod touch Generation 4 used an A4 processor, 256 MB of RAM, and was available with 32 or 64 GB of RAM for storage.

Source: Everymac, Wikipedia

iPod touch Generation 2 (8 GB, 2008)

The iPod touch Generation 2 is similar in features to the iPhone 3G, but lacks phone features, mobile phone networking, GPS, and a camera. While the back of the iPod touch Generation 2 is made of stainless steel (instead of plastic), its shape is similar to the iPhone 3G.

The iPod touch Generation 2 featured a multi-touch 3.5-inch display with 320×480 resolution, an accelerometer, ambient light sensor, Wi-Fi (802.11b/g), and 8, 16, or 32 GB of flash memory.

Compared to the original iPod touch, the Generation 2 model adds external volume controls on the left side of the device, an integrated speaker, external microphone (supported via the Apple Earphones with Remote and Mic), support for the Nike+iPod Sport Kit, a Genius feature to dynamically create playlists, and shaking the device to shuffle songs.

Source: EveryMac.com