iPhone 4S:

The only reason why the iPhone 4S failed to break any major records or attain lots of accolades was because most people were expecting the iPhone 5 when the 4S was introduced. There are very minute changes however, such as the fact that the phone now runs on a faster, A5x chip and has a more powerful camera, now weighing in at three. The phone was released in three variants; 16 GB, 32GB and 64 GB, with prices starting from $499 for the 16 GB edition.

iPhone 4:

The iPhone 4, upon its release, was a real game changer. After the tremendous success of the iPhone 3GS, people were rooting up for a better design and better features, so it is safe to say that expectations were high. The phone takes the resolution up to 640×960, and provides the first Retina display screen on any mobile device. It is available in three variants, namely the 8 GB, the 16 GB and the 32 GB one. The RAM in the phone has been doubled now to become 512 MB. The iPhone 4 has a 5 MP camera which has the capability of taking a picture up to a resolution of 2592×1536 pixels. The touch focus option is available, as is geo tagging and HDR. There is also a front facing VGA camera on the device.  Apart from this, the phone features a sleeker interface, without so many curves. The back is now plain and flat, and there are metal accents on the borders and corners.

iPhone 3GS:

The iPhone 3GS was a hugely popular phone, and after the iPhone 3G, it made a series of changes to the internal specifications of the phone. However, no changes were made on the outer aesthetics of the phone, which meant that on the outside, the phone simply resembled the iPhone 3G. It has a 3.5 inch screen with a resolution of 480×360, with 163 pixels per inch. The phone comes with a built in 8GB flash drive, and there is no slot for the memory card. It can record video with audio, and has a 3 megapixel still camera with photo editing and geo tagging features. Upon its release, the phone was very well received and carried the lead of its predecessor, making it the most widely anticipated smart phone out there. The release price was slated at $299 for the 8GB edition. However, at present, you can get the phone for free with a 2 year contract from any mobile company.