The battle between high-end smartphones got hotter still after the iPhone 4S became available in stores on Friday. While the iPhone 4S is not the iPhone 5 that was forecast by rumor mills, it is certainly not a lesser device. The phone has significant hardware upgrades even though it looks identical to the iPhone 4.

Apple has brought speech recognition to the masses with the 4S. The device is equipped with an intelligent assistant - Siri. The new smartphone received positive reactions from technology gadget reviewers especially for this piece of software.

The iPhone 4S does feature some important specs attributed to the phantom iPhone 5, like the 1GHz dual-core ARM Cortex-A9 processor, PowerVR SGX543MP2 GPU, an Apple A5 chipset and an 8 megapixel camera. It also has features like a 3.5-inch TFT Retina multi-touch display and is loaded with the Apple's latest Operating System - the iOS 5.

The iPhone 4S also comes with alternating antennae for better call reception, CDMA and GSM support, iCloud and Bluetooth 4.0 wireless technology. However, missing were prominent specs like edge-to-edge design, a larger display, 4G LTE and Near Field Communication (NFC) technology.

Meanwhile, Samsung's flagship, the Galaxy S2 smartphone (which some have dubbed the iPhone Killer) continues its strong march forward in the smartphone race, providing stiff competition for the iPhone 4S.

The Galaxy S2, which runs on the Android 2.3 Gingerbread OS and sports Samsung's TouchWiz UI, comes with an 8 megapixel flash-enabled camera and can record high-definition videos in 1080p, offering the richest video content on a smartphone. The phone also has a front-facing 2 megapixel camera for video chat.

The device, which was recently launched in the United States, has, according to reports, sold more than 10 million units since its launch in late April 2011. That figure doesn't including sales from the U.S., the largest market for smartphones.

On the other hand, Apple sold 20 million iPhones in the third quarter. Though the Galaxy S2's sales lag behind that of the iPhone, it does imply that the Samsung Galaxy S2 is the toughest rival Apple will face for its iPhone 4S.

Both phones promise blazing performances and are comparable in a number of areas, including price, processors, wireless syncing and sharing data with other devices and HD video capture. However, there still could be some differences between the two that could influence consumers when it comes to choosing one.

Size

Samsung Epic 4G Touch, as the phone is called on Sprint Nextel's network, measures 129.5 x 68.6 x 9.6 mm and weighs 129 grams, while the T-Mobile version measures 131 x 70 x 9 mm. As the AT&T version retains a 4.3-inch display, it is expected to measure 125.3 x 66.1 x 8.5 mm and weigh 116 grams. The Apple iPhone 4S, meanwhile, measures 115.2 x 58.6 x 9.3 mm and weighs 140 grams.

Display

The Samsung Galaxy S2 sports a 4.3-inch (4.52 for the Sprint Epic 4G Touch and T-Mobile USA's Galaxy S2) Super AMOLED screen with 800x480 screen resolution. The 4.3-inch screen comes with 217 ppi pixel density, while the 4.52-inch screen comes with 206 ppi. The iPhone 4S has a marginally smaller screen - at 3.5 inches - but boasts a Retina display of 960x640-pixel resolution at 326 ppi.

Operating System

Samsung's Galaxy S2 runs on the latest version of Google's smartphone Operating System, the Android 2.3.4 Gingerbread OS. Although the Android OS is capable of giving the user a very considerable amount of computing power, the fact that the Android apps market is cluttered with so many applications can make navigating it an annoying process.

Meanwhile, the iPhone 4S runs on iOS 5 - a free software update bringing over 200 new features to the iPhone, the iPad and the iPod touch, including wireless syncing, Twitter integration and widgets. The iOS 5 is touted as being very simple to use. The apps are arranged in grids of 12 across multiple screens, making navigation a potentially easier task.

Processor

The Sprint and AT&T variants of the Galaxy S2 are powered by a dual-core 1.2 GHz ARM Cortex-A9 Mali-400MP GPU Orion chipset, while the T-Mobile variant is powered by a 1.5 GHz dual-core Qualcomm APQ8060 processor. On the other hand, the iPhone 4S features a 1GHz dual-core ARM Cortex-A9 processor, PowerVR SGX543MP2 GPU and an Apple A5 chipset.

Camera

The Galaxy S2 packs an 8 megapixel camera with a single LED flash that is capable of capturing 1080p video footage; something which the iPhone 4 did not have. However, its upgrade - the 4S - has matched the Galaxy's specs.

Storage

The Galaxy S2 boasts 16GB of internal storage, expandable up to 32GB via a microSD card. The iPhone 4S comes in 16GB, 32GB and 64GB models. It doesn't support a MicroSD card slot. Apple has not revealed the RAM capabilities of the iPhone 4S

3G/4G Capabilities

The T-Mobile Galaxy S2 version has HSDPA 42 Mbps support while the AT&T version only has HSDPA 21 Mbps support and the Epic 4G Touch has Rev. A up to 3.1 Mbps. The Apple iPhone 4S, on the other hand, has HSDPA 14.4 Mbps and HSUPA 5.8 Mbps support. The iPhone 4S also has CDMA EV-DO Rev. A (800, 1900 MHz) technology.

Battery Life

The Samsung Galaxy S2 features a Li-Ion 1650 mAh battery offering talk time up to 540 minutes and standby up to 576 hours on 3G networks, while the iPhone 4S has a Li-Po 1,420 mAh battery, with 8 hours of talk time on 3G and up to 14 hours on 2G networks (GSM).

Price

The Galaxy S2 is priced at $199.99 with a two-year contract both on Sprint and AT&T, while the T-Mobile variant is priced at $229.99. The iPhone 4S costs $199 for the 16GB model, $299 for the 32GB model and $399 for the 64GB model.