LG Nitro HD smartphone, made available on AT&T Sunday, is expected to feel lots of burden from Samsung Galaxy S2, which is considered to be the best Android smartphone yet.

LG Nitro HD, featuring a 4.5-inch True HD AH-IPS display, is the first smartphone in the AT&T portfolio with a true high definition screen. It is considered to be the third 4G LTE smartphone for AT&T customers.

Taking advantage of LG's new proprietary True HD technology, Nitro HD's 4.5-inch AH-IPS (Advanced High-Performance In-Plane Switching) display supports resolutions up to 1280 x 720 pixels and offers unrivaled color accuracy, brightness, battery efficiency and performance.

LG said Nitro HD's 500 nit display luminance allows clear viewing in direct sunlight and RGB stripe pixels deliver incredibly accurate true-to-life color rendering.

LG Nitro HD, which runs on Google Inc.'s Android 2.3 Gingerbread OS, is adorned with dual-core 1.5 GHz Scorpion processor, 4.5-inch True HD AH-IPS display, 1 GB of RAM, 4 GB of internal memory with additional 16 GB microSD card included, 8-megapixel rear-facing LED flash camera with 1080p video capture and a secondary front-facing camera for video calls.

On the other hand, Samsung Galaxy S2 received overwhelming responses from around the world. 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 up to 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 LG Nitro HD 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 (about 206 ppi pixel density) 800 x 480 pixels Super AMOLED Plus capacitive touchscreen display. On the other hand, Nitro HD touts a 4.5-inch True HD AH-IPS (Advanced High-Performance In-Plane Switching) capacitive touchscreen with 1280 x 720 pixels resolution at about 326 ppi pixel density.

Size: Nitro HD comes with 5.27 x 2.67 x 0.41 inches dimension and weighs 4.5 ounces. On the other hand, Samsung Epic 4G Touch on Sprint comes with a 5.11 x 2.74 x 0.38 inches dimension and weighs 4.6 ounces, while the T-Mobile version has 5.11 x 2.71 x 0.37 inches dimension and weighs 4.77 ounces. As the AT&T version retains 4.3-inch display, it features 4.96 x 2.60 x 0.35 inches dimension and weighs 4.3 ounces.

Processor: Nitro HD features dual-core 1.5GHz Qualcomm APQ8060 processor with 1GB RAM. 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: The smartphones from LG and the variants of Samsung Galaxy S2 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 Nitro HD has a 1-megapixel camera for video chat.

3G/4G: Nitro HD will come with HSDPA 21 Mbps, HSUPA 5.76 Mbps and supports 4G LTE. 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: Both the smartphones from LG and Samsung have Android 2.3 Gingerbread operating system. It has been officially known that Galaxy S2 would be upgradable to Google Inc.'s smartphone operating system, Android 4.0 Ice Cream Sandwich, in early 2012. But LG haven't leaked any information regarding upgrading to Ice Cream Sandwich.

Ice Cream Sandwich is a combination of Gingerbread and Honeycomb in one unit. Android Head of Engineering Mike Claren announced that the new OS is Google's most ambitious release to date. The newest features arriving with Android 4.0 include widgets in a new tab, a customizable launcher, Gmail with offline search with a two-line preview and new action bar at the bottom, better voice integration, improved copy and paste and a new tabbed Web browser that allows up to 16 tabs.

WLAN/Bluetooth/USB: LG Nitro HD has Bluetooth 3.0 version with A2DP and HS along with microUSB 2.0 version. It also has Wi-Fi 802.11 b/g/n, Wi-Fi Direct, DLNA, and Wi-Fi hotspot.

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: Nitro HD has a fixed 4 GB internal storage with additional 16 GB microSD card included in the package that can be expandable up to 32 GB. But Galaxy S2 boasts of 16/32 GB internal storage and via a microSD card slot it can expand up to 32 GB.

Battery: 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. On the other hand, Nitro HD comes with a standard Li-ion 1830 mAh battery.

Pricing: Nitro HD is normally priced at $249.99 with a two-year AT&T contract, and in selected areas AT&T is offering $100 discount for LG Nitro HD. On the other hand, 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.