WinRT vs WinPRT

Windows Runtime (WinRT)

• Is a subset of native API that is built into Windows 8 and Windows RT operating systems.  
• Supports development in C++, C#, VB.NET, JavaScript and TypeScript. 
  
• Supports XAML framework and HTML5 for UI design.
  
• WinRT Apps:
• Are known as Windows Store Apps.  
• Natively support both the x86 and ARM architectures. 
• Run inside a sandboxed environment to allow for greater security and stability.

Windows Phone Runtime (WinPRT)

• Is a subset of native API that is built into Windows Phone 8 operating system. 
• Supports development in C++, C# and VB.NET.
• Supports XAML framework for UI design.
  

WinRT and WinPRT frameworks are similar in many areas. The following diagram shows the relationship between them in terms of the API surface area they implement:

1. The API surface area of WinRT is very large, with over 11,000 members. Area 1 in the diagram above represents the APIs that are not available on WinPRT.
2. The set of WinRT API adopted for WinPRT is represented by area 2 in the above diagram and consists of approximately 2,800 members. For some types, MS have not implemented certain members. For others they have added additional members to support phone-only features. In both cases, these differences are noted in the API reference documentation.
3. Phone specific key APIs are represented by area 3 in the diagram and total about 600 members. For example, brand-new APIs for speech synthesis and recognition, VOIP, and other features. 

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