Just would like to make clear, I cannot find straight answer. C# is general specification of this language done by MS, while Visual C# is implementation of this language, again done by MS?
So if we say we develop in C# (in visual studio e.g.) we develop in Visual C# actually.
Is that correct?
Yes, you've pretty much got it. Most of us just refer to it as C# though, since it is after all a Microsoft thing, and their implementation of the language is what most coders use (in Visual Studio).
An example of a C# compiler that is not Visual C# is the Mono compiler. The IDE that uses that compiler is MonoDevelop. Both are not Microsoft products, but do implement the C# programming language (as well as the CLR).
I don't think that "Visual C#" is a particularly commonly used term - C# is the language, so I would probably say that "Visual C#" refers just generally to C# development using the Visual Studio suite of products.
Like I said though it's not a commonly used term any more (and as you have pointed it out it is also a somewhat confusing term).
You can say that Visual C# is the tool that is part of Visual Studio, provided my Microsoft used to create programs in the C# language.
There is the ECMA-334 C# Language specification, that defines the language.
There are other tools to create programs in C#, like SharpDevelop or MonoDevelop.
This whole "visual C#" has caused me much unnecessary grief (including one during an interview , given I had never heard of the term 'visual C#' and apparently the interviewer didn't even know what it was and was just trying to put checkmark beside qualifications). To sum, Visual C# doesn't exist. It's just C#, we should file a petition to remove that stupid qualifier.
Visual C# is the name of compiler (and IDE). C# is the language. It is the same as Borland C++ and C++ (first is the specific compiler). Or MySQL and SQL.
For all the answers that "Visual C# is C# developed in Visual Studio" - I would point out that the C# Compiler (CSC.EXE) is not part of Visual Studio but is delivered as part of the Microsoft .net Framework - which is completely independent of the Microsoft Visual Studio line of development tools.
In that it has any meaning at all (beyond the initial marketing idea that it would appeal to Visual Basic developers, who were the majority of Windows developers on launch day) I'd say it refers to C# compiled by the Microsoft implementation of the .net Framework.
Whether or not Roslyn compiles "Visual C#" or "C#" is anyones guess.
C# is a kind of programming lang, something like Java, Ruby, Python.
Visual C# means Microsoft Visual Studio/C#， it's IDE for programming C#.
u also can write C# code in notepad.
来源：https://stackoverflow.com/questions/5296058/c-sharp-and-visual-c