With the iPod Touch set to debut any second, I've been getting a lot of mail and phone calls asking: "Which should I buy? The iPhone or the Touch?" Here's a quick reference to help you make your decision.
Cost. At $299, the iPod Touch costs $100 less than the $399 iPhone. If you're looking for the least expensive entry point, your choices are the 8GB Touch or a refurbished 4GB iPhone. The Touch has double the memory for the same price.
Form Factor. The iPhone is bigger and heavier than the Touch. It weighs in at 4.8 ounces and 11.6 mm depth versus the Touch's slim 4.2 ounces and 8mm thickness. Not a huge difference to be sure but those extra 4 mm definitely feel different in the hand.
Built-ins. The iPhone offers a built-in microphone, speakers and 2.0 megapixel camera. The Touch does not. You can't snap a photo and email it on the go with the Touch the way you do with iPhone.
Contract-free use. The iPhone is designed to be used with a monthly service fee. The Touch is contract-free out of the box. The iPhone requires activation through semi-nefarious hacking before it can be used without a contract and/or phone service.
Hackability. The Touch is probably just as hackable as the iPhone but the iPhone is a known quantity.
EDGE. Surfing on the Touch is a WiFi-only prospect. The US iPhone offers EDGE for when you're away from WiFi hotspots. Even with EDGE, though, coverage is spotty.
From. http://www.tuaw.com/2007/09/10/iphone-versus-ipod-touch-what-to-buy/