External Differences
The iPhone 5 configurations have a 4" (diagonal) widescreen multi-touch IPS LED-backlit 1136x640 native resolution (326 ppi) "Retina" display, which has "integrated touch technology" so the pixels themselves act as a touch-sensitive digitizer. The iPhone 4 and iPhone 4S models likewise have a multi-touch IPS LED-backlit "Retina" display, and it likewise is 326 ppi, but the display is only 3.5" 960x640, so it's shorter but the same width. The iPhone 4 and iPhone 4S have a separate touch sensitive digitizer, which is one reason they are thicker.
Size-wise, the iPhone 5 configurations are only 0.30 of an inch (7.6 mm) thick and weigh 3.95 ounces (112 g), which Apple proudly proclaims is "18% thinner and 20% lighter" than the iPhone 4S. In person, the iPhone 5 is so light it almost feels hollow or fake, but you get used to it in time. By comparison, the iPhone 4S is 0.37 of an inch thick and is a comparatively hefty 4.9 ounces (140 g). The iPhone 4 models are the same dimensions as the iPhone 4S but weigh slightly less -- 4.8 ounces (137 g).
The iPhone 5 has a largely aluminum housing with "diamond cut" chamfered aluminum around the sides and a mostly aluminum back offered in either a matte black finish or a matte silver finish and corresponding glossy black or white glass fronts. By contrast, the iPhone 4 and iPhone 4S models use the same general stainless steel body design and likewise have a thin metal "band" that wraps around the sides of each phone. However, both the front and back are black or white glass, which adds considerably to relative thickness and weight.
Finally, the iPhone 5 has a bottom mounted headphone jack and a smaller, easier-to-use USB 2.0-based "Lightning" port to connect the iPhone 5 to a computer, power adapter, or stereo, as well as built-in speakers and three noise canceling microphones. The iPhone 4 and iPhone 4S models have a more convenient top mounted headphone jack and a larger, but more finicky, 30-pin "Dock Connector" that provides much greater compatibility with iPhone-compatible devices made since its inception in 2007, as well as smaller built-in speakers and two noise canceling microphones.
All iPhone 5 models, even the "CDMA" models (which support an assortment of GSM connectivity, too), have an access panel on the right side of the metal band for the enclosed tiny Nano SIM card (or UIM for the China-only model), whereas the the iPhone 4S models and the iPhone 4 (GSM) likewise have an access panel in roughly the same place, but they use the now older Micro SIM standard. The iPhone 4 (CDMA) does not have an access panel or a SIM card.
The iPhone 4 (GSM) has three antenna "breaks" in the metal band (one on the top and one on each side toward the bottom) whereas the iPhone 4 (CDMA), iPhone 4S, and iPhone 5 have four (two on both sides toward the top and bottom).
Camera Differences
The iPhone 4, iPhone 4S, and iPhone 5 all have dual cameras, but there are important quality differences between them.
The iPhone 5 and iPhone 4S both have a rear 8 megapixel camera, which includes support for 1080p 30 FPS video recording and Panorama mode. However, the iPhone 5 rear camera has better video stabilization, the ability to take still photos while also recording video, and face detection. It is worth noting, however, that the rear camera on the iPhone 5 is only modestly better than the rear camera in the iPhone 4S in many real-world tests.
The iPhone 5 additionally has a front 1.2 megapixel, 720p "FaceTime HD" camera whereas the iPhone 4S only has a VGA quality front-facing camera, both intended primarily for use with FaceTime video conferencing.
By contrast, the rear camera on the iPhone 4 only is capable of shooting 5 megapixel still photos and 720p 30 FPS video and it has the same VGA quality front-facing camera as the iPhone 4S.
Identification Differences
Although the aluminum back on the iPhone 5 initially made it easy to spot, this has become more difficult with the introduction of subsequent models.
Consequently, one simple way to identify the iPhone 4, iPhone 4S, and iPhone 5 models, as well as collectively differentiate them from all other iPhone models, is by referencing the Model Number listed in small type on the back of the phone.
The relevant model numbers are:
iPhone Model Model Number
iPhone 4 (GSM) A1332
iPhone 4 (CDMA) A1349
iPhone 4S (Global) A1387
iPhone 4S (China) A1431
iPhone 5 (GSM/North America)
iPhone 5 (GSM AWS/North America)
A1428
iPhone 5 (CDMA)
iPhone 5 (GSM/International)
A1429
iPhone 5 (CDMA China/UIM/WAPI) A1442
Given the above, it clearly is not possible to differentiate between the iPhone 5 devices by model number alone, but for the purpose of this Q&A, it is sufficient to note that A1428, A1429, and A1442 refer to the iPhone 5 rather than another iPhone model. EveryiPhone.com also provides an in-depth evaluation of the differences between the iPhone 5 configurations that may be of interest.
EveryiPhone.com's Ultimate iLookup feature -- as well as the EveryMac app for iOS 5 or higher and Android -- also can precisely identify these iPhone models by Order Number (referred to as "Model" within the iOS "Settings" app under General > About), and their Serial Numbers, as well.
Battery Life Differences
Apple reports that all of these devices provide an estimated maximum of 40 hours of audio playback and 10 hours of video playback, but provide different numbers for voice, mobile Internet, and Wi-Fi use:
iPhone 4 iPhone 4S iPhone 5
Talk Time (3G) 7 Hours 8 Hours 8 Hours
Internet Use (3G) 6 Hours 6 Hours 8 Hours
Internet Use (4G/LTE) None None 8 Hours
Internet Use (Wi-Fi) 10 Hours 9 Hours 10 Hours
Of course, these Apple-provided estimates are for performing a single task. In the real-world, one is likely to mix different tasks and battery conservation can be quite useful.
Wireless Connectivity & Data Differences
Wireless connectivity is quite different amongst the iPhone 4, iPhone 4S, and iPhone 5.
The iPhone 5 models are the only ones to mostly support 4G/LTE, although the bands supported by different configurations vary. Specifically, the A1428 iPhone 5 (GSM/North America) and (GSM AWS/North America) support LTE bands 4 and 17 (and the AWS model adds AWS support on carriers that support the standard), the CDMA A1429 iPhone 5, supports LTE bands 1, 3, 5, 13, and 25, the "International" GSM A1429 iPhone 5, supports LTE bands 1, 3, and 5. The A1442 iPhone 5 (CDMA China/UIM/WAPI) does not support LTE.
All iPhone 5 models support UMTS/HSPA+/DC-HSDPA (850, 900, 1900, 2100 MHz), and GSM/EDGE (850, 900, 1800, 1900 MHz), but only the A1429 CDMA version supports CDMA EV-DO Rev. A and Rev. B (800, 1900, 2100 MHz). The A1442 China-only model does not support 2100 MHz CDMA EV-DO.
The iPhone 4S models support both GSM and CDMA networks -- UMTS/HSDPA/HSUPA (850, 900, 1900, 2100 MHz), GSM/EDGE (850, 900, 1800, 1900 MHz), and CDMA EV-DO Rev. A (800, 1900 MHz). HSDPA is up to a theoretical maximum of 14.4 Mbps.
The earlier iPhone 4 models, support either GSM or CDMA networks, but not both, and each device only supports a maximum theoretical HSDPA download speed of 7.2 Mbps.
All three models support 802.11n Wi-Fi, although the iPhone 4 and iPhone 4S only support it on the 2.4 GHz frequency and the iPhone 5 supports both the 2.4 GHz and 5 GHz frequency. The iPhone 5 and iPhone 4S support Bluetooth 4.0 and GLONASS in addition to GPS, whereas the older iPhone 4 only supports Bluetooth 2.1+EDR and GPS, without its former Soviet counterpart. The China-only iPhone 5 and iPhone 4S models add "WAPI" support as required by the Chinese government, as well.
Unfortunately, it also is worth noting that Apple disabled the CDMA capability on unlocked iPhone 4S models purchased in the United States. As first discovered by iDownloadBlog, the Verizon iPhone 5 model was sold unlocked, albeit with a two year contract, but this still made it the top choice for Americans interested in traveling outside of the US. The iPhone 5 (GSM/LTE/AWS/North America) was offered on T-Mobile unlocked but generally bound by a contract, as well.
Internal Differences
The iPhone 5 packs a "twice" as fast dual core 1.3 GHz Apple A6 processor as well as 1 GB of RAM, compared to the iPhone 4S -- which has a 1 GHz dual core Apple A5 processor and 512 MB of RAM -- and the iPhone 4, which has a single core 1 GHz Apple A4 processor and 512 MB of RAM.
Although capacities have shifted over the years, the iPhone 4 models originally were offered with 16 GB and 32 GB of storage and the iPhone 4S models originally were offered with 16 GB, 32 GB, and 64 GB of storage. Later, both models were offered with 8 GB of storage. Of course, on the used market, all of these capacities are readily available.
The iPhone 5 was offered with 16 GB, 32 GB, or 64 GB of storage.
iOS Support & Software Differences
The iPhone 4, iPhone 4S, and iPhone 5 models all are capable of running iOS 6 and iOS 7, but only the iPhone 5 fully supports all features on both versions of the operating system. The iPhone 5 fully supports all features on iOS 8, as well.