When you say iPod Touch 2G (2nd Generation)and 3G (3rd Generation), you can’t differentiate both when it comes to look, both are alike (at least 99 %).
What is the difference between iPod touch 2G and 3G?
Both the iPod touch 2G and 3G feature multitouch, accelerometer, WIFI, Niki+iPod support and only flash memory storage of differing capacity — 8, 16, or 32 GB for the 2G and 8, 32, or 64 GB for the 3G.
The 8 GB configuration of the iPod touch “3G” series is a reissue of the 8 GB configuration of the iPod touch 2G that came before it, just sold for US$199 instead of US$229.
Although they are sold as a single line i.e iPod Touch 3G with 8 GB, 32 GB, or 64 GB of storage — the 32 GB and 64 GB models are significantly different internally from the 8 GB one.
Internally, the 32 GB of 64 GB models have more in common with the iPhone 3GS with advertised “50% faster performance” due to 800 MHz Samsung ARM processor that powers the iPhone 3GS and OpenGL ES 2.0 support for superior graphics performance as well as 256 MB of RAM.
The 8 GB model, on the other hand, uses the same 533 MHz Samsung ARM as the iPod touch 2G models and 128 MB of RAM.
The 32 GB and 64 GB models also add “Voice Control” navigation capability and a “VoiceOver” screen reader – the “world’s first gesture-based screen reader” but the 8 GB model is not powerful enough to support either feature.
Also, You will notice that Battery life is dropped on iPod Touch 3G when you compare it with iPodTouch 2G.
Here, is the chart which will give you the clear view of the differences between the two devices:
If you want to identify an iPod touch, if it’s 2G or 3G: Please check below video by SilverWing9999: