Difference between System::Double vs double

[Arctic Inferno]

They’re both double-precision floating-point numbers,
so expected to have identical precision.
Visual Studio 2010 editor displays System::Double in black,
while double is displayed in blue.
Speed/performance?

[soranz]

They r the same. No difference that I know except that 'double' is faster to type.

[webJose]

That's the class that is used to box doubles. There are others: System::Int32 to box int's, System::Boolean to box bool's, etc.