Similar to previous iPod touch models, the iPod touch (4th Generation) is in many ways a "phone-less" equivalent of the iPhone available at its time of release, which was the iPhone 4.
The 4th Generation iPod touch lacks 3G/EDGE mobile networking, A-GPS (though it can triangulate position via Wi-Fi), and a digital compass. It also features a lower-quality, approximately 0.70-megapixel rear camera without a flash.
Despite these omissions, the iPod touch (4th Generation) is largely similar to its contract-bound counterpart. It includes a 3.5" 960x640 (326 ppi) "Retina display" (though a non-IPS version), FaceTime video calling via Apple ID or email, an integrated microphone, a front-facing VGA camera, iMovie editing support, a 3-axis gyroscope, and 720p video recording (using the lower-quality camera).
Like the iPhone 4, the 4th Gen iPod touch is powered by an Apple A4 processor but has only 256 MB of RAM (versus 512 MB) and was offered in 8 GB, 32 GB, or 64 GB storage capacities. Apple's estimated battery life is 40 hours for music playback and 7 hours for video.