Is there any physical design difference between iPhone 4 and iPhone 4s, such as a different material for the apple on the back or does it say it anywhere on the phone??
The only physical difference is one of the antennas has shifted to the side of the iPhone with the SIM card holder. This makes it different than the GSM iPhone 4, but not the CDMA iPhone 4.
If you're aiming for what I think you are, I'd suggest to talk to Siri as loud and often as possible at public places. So nobody can miss that it's the *new* iPhone 4S. 😉
Is there any physical design difference between iPhone 4 and iPhone 4s, such as a different material for the apple on the back or does it say it anywhere on the phone??
You can tell the difference from an iPhone 4 because it will have two 'bands' on the side of the vibrate switch, and a SIM card insert on the other side of the phone.
The iPhone 4 either has either one or the other - not both, as the 4S does.