Microsoft has released Windows Phone 7.5 on Sept 27th 2011. The Operating system itself been initially been called as “Windows Phone 7.5” code named as “Windows Phone MANGO”.

The underlying operating system version is Windows Phone 7.1, even though it is been marketed as “Windows Phone 7.5”. There is been lots of confusion among people because Phone is called as “Windows Phone 7.5” and OS version is been listed as “7.1”. So to clear the confusion here is the solution.

The following table describes the Windows Phone releases and corresponding operating system version numbers.

Windows Phone release OS version
Windows Phone 7.0 Windows Phone 7.0 OS
Windows Phone 7.5 Windows Phone 7.1 OS

Typically a Windows Phone 7.5 device is a Windows Phone that is running Windows Phone OS 7.1. Although the OS internally identifies itself as version 7.1, it is marketed as version 7.5 in all published materials intended for end-users.

So don’t get confused people, it is all same under the hood. Same bottle of wine with two different stickers on it. Smile

Refer to Windows Phone Application Compatibility documentation available with MSDN. [for more information]

Read more on What’s new in Windows Phone 7.5