Apple, which unveiled iPhone 4S on Oct. 4, is getting flying off the shelves despite its battery draining problem for which the Cupertino, California-based company would be issuing a fix in the next few days.

The smartphone, which missed some prominent specs like edge-to-edge design, a larger display, 4G LTE and Near Field Communication (NFC) technology, sold 4 million units during the opening weekend.

However, it has significant upgrades over its predecessor including 1GHz dual-core processor, PowerVR SGX543MP2 GPU, an Apple A5 chipset, Siri voice assistant and an 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.

Recently, Apple has announced the availability of the iPhone 4S in Hong Kong, South Korea and 13 additional countries beginning Nov. 11.

Meanwhile, Samsung Galaxy Nexus is seen as the closest competitor to iPhone 4S. Galaxy Nexus, which runs on Android Ice Cream Sandwich, was launched by Google at an event in Hong Kong Oct. 18.

Galaxy Nexus, which was also known as Google Nexus Prime and Google Nexus 4G, comes with dual-core 1.2GHz processor, 4.65-inch screen, 1 GB of RAM, NFC, 4G LTE support, 5-megapixel rear-facing camera with 1080p video capture and 1.3-megapixel front-facing camera for video calls.

Let's see how these two flagship phones fare against each other.

Display: iPhone 4S, comes with 3.5-inch TFT Retina multi-touch display that may give a resolution of 960 x 640 pixels at 326 ppi density. On the other hand, Galaxy Nexus sports a 4.65-inch high-definition Super AMOLED display that may give a resolution of 1280 x 720 pixels with about 316 pixel per inch (ppi) density.

Size: iPhone 4S comes with 115.2 x 58.6 x 9.3 mm and weighs 140 grams while Galaxy Nexus has 135.5 x 67.94 x 8.94 mm dimension and weighs 135 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, Galaxy Nexus will feature 1.2GHz dual-core Cortex-A9 CPU, TI OMAP 4460 chipset with 1GB RAM.

Operating System: Apple's iPhone 4S runs on the newest iOS 5 that comes with 200 new features that will include an improved Notifications System, Newsstand and iMessage. On the other hand, Galaxy Nexus will run on the latest version of Google Inc.'s smartphone operating system, Android 4.0 Ice Cream Sandwich.

Camera: iPhone 4S sports an 8-megapixel camera with 1080p HD video capture capability, while Galaxy Nexus will sport a 5-megapixel camera with 1080p video capture. For video calls, Galaxy Nexus will have a 1.3-megapixel front-facing camera while iPhone 4S comes with a secondary VGA camera.

Connectivity: Apple iPhone 4S has HSDPA 14.4 Mbps, HSUPA 5.8 Mbps support and also has CDMA EV-DO Rev. A (800, 1900 MHz) technology while Galaxy Nexus has HSDPA 21 Mbps, HSUPA 5.76 Mbps and 4G LTE support.

Storage: iPhone 4S comes with fixed 16/32/64 GB internal storage while Galaxy Nexus will have a fixed 16/32 GB internal storage.

WLAN/Bluetooth/USB: iPhone 4S has Wi-Fi 802.11 b/g/n and Wi-Fi hotspot while Galaxy Nexus will have Wi-Fi 802.11 a/b/g/n, dual-band, DLNA, Wi-Fi hotspot. Galaxy Nexus will have Bluetooth 3.0 version with A2DP along with microUSB 2.0 version while iPhone 4S has advanced Bluetooth version 4.0 with A2DP along with USB version 2.0.

NFC: Unlike iPhone 4S, Galaxy Nexus offers support to Near-Field Communication (NFC) that allows for simplified transactions, data exchange, and wireless connections between two devices in close proximity to each other. It is expected to become a widely used system for making payments by smartphone in the United States.

Battery: iPhone 4S has a Li-Po 1420 mAh battery, with 8 hours of talk time on 3G networks, up to 14 hours on 2G networks (GSM) and a standby time of 200 hours. On the other hand, Galaxy Nexus will come with a standard 1750 mAh battery.

Pricing: Galaxy Nexus will hit the stores in mid-November in the U.S., and as far as the pricing goes, nothing has been announced yet.

With a two-year contract, 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.