Why not use
Mono? I assume you're asking what the difference is between a C# compiler and Borland C#Builder. Microsoft, Borland, and Novell all offer C# compilers - Borland's is called C#Builder, Microsoft's is called Visual Studio .NET, and Novell's is called Mono. Mono is free software and open source, and the
Monodevelop project provides an IDE. Borland offers a free 30-day trial, but why bother?
My advice: go with Mono.