The attempted distinction is intuitive to me, but I for one can't think of the words for it.
Jane was hired as a contractor to deliver a business process application in C#. The contract to hire Jane was a work-for-hire contract without the explicit copyright transferring language... /end of example.
I would presume that Jane's final work product is an arrangement of previous work by Anders Hejlsberg (who lead the original C# development team) and other employees of Microsoft. Is this not a sound line of reasoning?
Similarly, just because you write code in C# and then send it to code I wrote, which translates it to CIL, that doesn't mean that any of your code is actually an arrangement of my code. Your code just conformed to the required input of my tool (the C# compiler).