The Visual C++ Redistributable Packages install run-time components of Visual C++ libraries. These components are required to run C++ applications that are developed using Visual Studio 2015 and link dynamically to Visual C++ libraries. These package can be used to run such applications on a computer even if it does not have Visual Studio 2015 installed. These packages install run-time components of these libraries: C Runtime (CRT), Standard C++, MFC, C++ AMP, and OpenMP.
To find out what's new in Visual Studio 2015, see the Visual Studio 2015 Release Notes. For a list of fixed bugs and known issues, see the Visual Studio 2015 KB Article.