The iPhone 4
The iPhone 4 came in two distinct colors: White and Black
The iPhone 4 has some subtle differences between it and the 4s. The biggest visual difference is the antenea. The iPhone 4 has a break in the antenea at the top near the headphone jack. This is only on the iPhone 4 for AT&T. This phone is available thru AT&T; Sprint and Verizon and presently only comes in the 8GB both black and white.
The iphone 4 originally came in sizes 8GB, 16GB and 32GB. Presently only the 8GB is for sale through the Apple website and stores.
Here are the basic controls for the iPhone 4
For more information and technical specs you can view this site
Updated 11/12/12.