The battle of smart phone heated up after release of iPhone 4, the fourth generation Apple iPhone once again boost the competition of smart phone and manufacturers scuttling to offer iPhone killer phones.

Motorola Droid X, the Google Android powered smart phone is one of the top contenders of iPhone 4. Droid has been receiving better reviews from several analysts.

Where the iPhone 4 measuring 4.5 x 2.2 x 0.37 inches, comes with 3.5 inch display with 640×960 pixel resolution, Motorola Droid measuring 5 x 2.6 x 0.4 inches with 4.3 inch big display with WVGA and resolution 854×480.

iPhone 4 come with Apple’s latest mobile operating system iOS 4, which promises features like multitasking, spell check, iBooks and folders.

But still OS doesn’t support email attachment and built in photo editing feature. Droid X comes with Android 2.1 OS, and will soon get Android 2.2 update.

Droid comes with new version of MotoBlur, Motorola’s OS that brings together messages from social networking services. iPhone will be able to run more than one programme at a time and Droid also offers support for multitasking.

iPhone comes with 16GB and 32GB memory capacity but lacks a memory expansion slot. Droid comes with 8GB onboard memory and 16GB pre-installed microSD support.

Memory can expand upto 32GB. Where iPhone has 5 MP with LED flash camera, Droid has 8 MP camera with auto focus, auto zoom, dual LED flash and image editing tools.

iPhone 4 allow users to do video conferencing with its second VGA camera, Droid doesn’t have call camera. iPhone is providing connectivity options include Wi-Fi, Bluetooth, HDMI and GPS and Droid offers connectivity options include Stereo Bluetooth 1.5, Wi-Fi, USB 2.0 HS, HDMI and GPS.

iPhone 4 has better battery life compared to its predecessors. The phone promises 7 hrs of 3G talk time, 6 hrs of 3G browsing, 10 hrs of Wi-Fi browsing, 10 hrs of video and 40 hrs of music playback.

Where Droid X offers 8 hrs of talk time. iPhone users can access over 225000 apps from Apple’s app store. And Droid users can access around 65000 apps.

iPhone new OS can disappoint users on flash front because it doesn’t support Adobe Flash, but Motorola Droid supports Adobe flash 10.1.