Answer
ArcGIS Desktop 8.3 includes the ArcObjects Developer Kit which provides support for the programming languages Visual Basic.NET and C# from Microsoft’s Visual Studio.NET.
Visual Studio .Net is a support development environment for ArcGIS Desktop, ArcGIS Engine Developer Kit, and ArcGIS Server at version 9. The ArcGIS 9 products come with the ArcGIS Developer Kit which contains .NET samples, tutorials, and documentation to help developers get started.
ArcObjects developers wishing to use Visual Studio .NET should use the ESRI primary interop assemblies included with ArcGIS.