.NET Framework and .NET Core are common software application development framework can be used to build a variety of software, including Web applications, mobile applications, desktop applications, cloud services, micro-services, API, games and networking applications program.
.NET Framework: only run on a Windows system,
Core the .NET : General development framework cross-platform software application that can be used to build software applications for the Windows, Linux and MacOS.
.NET Core next version after 3.0 will be the .NET 5 . This will be the next major version of the .NET family.
In the future there will only be a .NET, you will be able to use it to develop Windows, Linux, macOS, iOS, Android, tvOS, watchOS and WebAssembly and so on.
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Qt : is a Qt Company in 1991 by the development of cross-platform C ++ GUI application development framework.
It can develop GUI program can also be used to develop non-GUI programs such as console tools and servers.
Qt supports MS / Windows, Unix, Linux, Macintosh - Mac the X-OS platform.
Visual Studio Tools qt : Visual Studio development of QT plugin
Core Qt : QT's core module, all other Qt modules rely on this module.