What is the difference between the iPhone and the itouch?

The iphone and iPod touch are closely related - and not just because they look alike. Starting with the iphone 4 and 4th-generation iPod touch, they share the same OS, support for FaceTime video conferencing, Retina Display screens, and Apple's A4 processor. But, even though the touch is often called an iphone-without-the-phone, there are some significant differences between the two devices.