There is a difference in the description on MSDN, however, I do not understand what the text means what the difference is.
The GetClassName
function retrieves the name of the class to which the specified window belongs.
The RealGetWindowClass function retrieves a string that specifies the window type.
As an example using windows calc.exe
From GetClassName you get "SciCalc"
From RealGetWindowClass you get "#32770"
I guess what I'm really asking then is what is a "Window type" versus a "Window class name"?