Windows Phone Tango will require just 256MB of RAM compared to the 512MB minimum on Windows Phone Mango. This in turn limit the support for apps allowing a limited number of apps to be available for those lower end hardware devices based on the apps requirements
Other limitations for devices with 256MB include,
source - WP7Forum
Other limitations for devices with 256MB include,
- Inability to play videos with a bitrate over 4Mbps
- Inability to manage podcats on your Windows Phone
- Inability to receive live tile updates from third party apps
- Inability to automatically upload photos to your SkyDrive
The camera requirement has now been reduced to 3 megapixels. Allowing manufacturers to add lower end cameras to Windows Phones, compared to the 5 megapixel minimum no Windows Phone Mango.
However Windows Phone Tango will also bring a number of improvements to the platform, which should make it's way to all Windows Phone devices as we await the launch of Windows Phone 8 (Apollo). This improvements include;
- Ability to import/export contacts from your SIM card
- Updates to roaming options
- Ability to download and update apps through Zune
- More pre-installed apps
- Support for new countries.
- Improved MMS support allows to attach multiple photos, videos and audio files.
While the other mobile operating systems continue to expand their hardware requirements Windows Phone plans to try and draw in customers who still prefer their feature phones.
source - WP7Forum