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, ag
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).