Apple Inc. received overwhelming positive responses for iPhone 4S that sold 4 million units during the opening weekend. Despite having fewer features when compared to Samsung Galaxy S2, iPhone 4S promises blazing performance with its A5 chipset and the latest iOS 5.

Apple Inc. unveiled iPhone 4S, instead of the eagerly-anticipated iPhone 5, on Oct. 4. The smartphone missed some prominent specs like edge-to-edge design, a larger display, 4G LTE and Near Field Communication (NFC) technology.

However, iPhone 4S featured some important upgrades that were rumored to be a part of the imaginary iPhone 5, like the 1GHz dual-core ARM Cortex-A9 processor, PowerVR SGX543MP2 GPU, an Apple A5 chipset and a 8-megapixel camera. It also has a 3.5-inch TFT Retina multi-touch display and is loaded with the latest Apple operating system iOS 5.

It also comes with alternating antennae for better call reception, CDMA and GSM support, a personal assistant called Siri, iCloud and Bluetooth 4.0 wireless technology. The Apple smartphone has a Li-Po 1,420 mAh battery, with 8 hours of talk time on 3G networks and up to 14 hours on 2G networks (GSM).

On the other hand, Galaxy S2, which received overwhelming responses from around the world, officially sold 10 million units since its global launch in late April.

Galaxy S2, which runs on Android 2.3 Gingerbread OS and sports Samsung's TouchWiz UI, comes in three variants, on AT&T, T-Mobile and Sprint, whose version is called Samsung Galaxy S2 Epic 4G Touch. All versions of the Galaxy S2 will get 4G treatment, offering data speed upto four times faster than Apple's iPhone 4.

Galaxy S2 comes with an 8-megapixel camera with flash and can record HD video in 1080p offering the richest video content on a smartphone. The phone also has the front-facing 2-megapixel camera for video chat.

Here is a comparison between Apple iPhone 4S and Samsung Galaxy S2:

Display: Both the T-Mobile and Sprint versions of Galaxy S2 has 4.52-inch display screen whereas AT&T version retains 4.3-inch screen of original Galaxy S2 version sold worldwide. The Galaxy S2 Epic Touch 4G comes with 4.52-inch (~206 ppi pixel density) 800 x 480 pixels Super AMOLED Plus capacitive touchscreen display.

Size: Apple iPhone 4S comes with 115.2 x 58.6 x 9.3 mm and weighs 140 grams. On the other hand, Samsung Epic 4G Touch on Sprint comes with a 129.5 x 68.6 x 9.6 mm dimension and weighs 129 grams, while the T-Mobile version has 131 x 70 x 9 mm dimension. As the AT&T version retains 4.3-inch display, it is expected to feature 125.3 x 66.1 x 8.5 mm and weighs 116 grams.

Processor: iPhone 4S, which comes in an A5 chipset, is powered by 1GHz dual-core ARM Cortex-A9 CPU, PowerVR SGX543MP2 GPU. On the other hand, the Sprint and AT&T variant of the Galaxy S2 is 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.

Camera: Both the smartphones sport a rear-facing 8-megapixel LED flash camera with 1080p HD video capture capability. Galaxy S2 has an additional 2-megapixel front-facing camera for video calling while iPhone 4S has a VGA camera for video chat.

3G/4G: Apple iPhone 4S has HSDPA 14.4 Mbps, HSUPA 5.8 Mbps, and CDMA EV-DO Rev. A (800, 1900 MHz) technology support. On the other hand, the T-Mobile Galaxy S2 version has HSDPA 42 Mbps support while the AT&T version has HSDPA 21 Mbps support. And Epic 4G Touch has Rev. A up to 3.1 Mbps.

Operating System: Apple's iPhone 4S runs on iOS 5, which is the newest of the OS versions. The new iOS 5 comes with 200 new features that will include Improved Notifications System, News Stand and iMessage.

Samsung's Galaxy S2, on the other hand, runs on Google Inc.'s smartphone operating system, Android 2.3 Gingerbread OS, but it is expected that an upgrade to the latest OS Android 4.0, Ice Cream Sandwich will come once Samsung Galaxy Nexus arrives.

WLAN/Bluetooth/USB: iPhone 4S has Wi-Fi 802.11 b/g/n support and the phone can be used as a Wi-Fi hotspot. Apple's phone uses the most advanced 4.0 version Bluetooth with A2DP along with USB version 2.0.

Galaxy S2 has Wi-Fi 802.11 b/g/n DLNA support and an added Wi-Fi Direct feature. Samsung's phone uses 3.0+HS version Bluetooth with A2DP and EDR along with MHL microUSB version 2.0 for HDMI support.

Storage: iPhone 4S has fixed 16/32/64 GB internal storage, while Galaxy S2 boasts of 16/32 GB internal storage and via a microSD card slot it can expand up to 32 GB.

Drop Test: A lot has been written about the red hot battle between both these smartphones. However, the battle of wits took a turn when two were dragged to a brutal, unforgiving drop test. The two warring smartphones were dropped thrice - first from waist-high, second time from the shoulder level, and the third was a face down drop.

Though iPhone 4S was not highly damaged after the first two drops, the glass casing of the phone was completely shattered when it was dropped face down. Galaxy S2 stood the clear winner in the drop test, wrapped all around with plastic and Corning Gorilla Glass on the front. It remained scratch-less at the end of the test.

Battery: The Apple smartphone has a Li-Po 1420 mAh battery, with 8 hours of talk time on 3G networks and up to 14 hours on 2G networks (GSM). Samsung Epic Touch 4G has Li-Ion 1800 mAh battery support, which will offer more than 10 hours of talk time, while AT&T versions retain Li-Ion 1650 mAh battery found in original Galaxy S2. The T-Mobile variant of Galaxy S2 has Li-Ion 1850 mAh battery support.

Pricing: With a two-year contract, the iPhone 4S costs $199 for the 16GB model, $299 for the 32GB model and $399 for the 64GB model. Apple-listed prices for a contract-free phone in the United States are $649 for the 16GB model, $749 for 32GB and $849 for the 64GB.

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.