Everyone loves naming conventions and product code names :) I’ve see a few people mislead by blogs and so called “.com press” to the point of confusion about what Windows Phone 7.5 Refresh and Windows Phone SDK 7.1.1 actually are in reality.
So let’s clarify:
Windows Phone 7.5 Refresh – is the name of the refresh update to Windows Phone OS that allows for broad reach to new markets and languages, previously not supported in Windows Phone 7.5 OS. This update also provides support for market specific hardware running 256MB of RAM. Finally the 7.5 Refresh provides integration to market specific alternatives to Facebook and Twitter for regions that primarily use those instead. Outside of those updates to the feature set, this OS is identical to Windows Phone 7.5 and should not affect your current phone or it’s usage.
Windows Phone SDK 7.1.1 Update – is the name of the update to the SDK for Windows Phone that provides emulators to test your application with new languages and regions, as well as new 256MB and 512MB emulator images as part of the Windows Phone 7.5 Refresh. Outside of those changes and some bug fixes, the SDK is feature identical to Windows Phone SDK 7.1 and most applications written with 7.1 will run on Windows Phone 7.5 Refresh OS. Few applications that have been identified as using more memory have had their developers notified by Microsoft. I encourage you to test your application yourself, just to be sure. It is your choice if you do not plan on releasing your application in Global marketplace or choose to not provide your application in markets supporting Windows Phone 7.5 Refresh or specifically identify that your application requires are high-memory device. Note that this is an Update to the 7.1 SDK, so be sure you have that installed. More Info (Also this update is needed if you are running Windows 8 Consumer Preview)
If you have any questions please comment or spark a conversation on twitter @NikitaP