Imagine this situation. You have a machine that is going to do some packaging The output of this processes are packages How do you call the "raw material" that you use for packaging?
Now, I can see that this can be very ample, for example if there are already plastic packages ready to be filled and sealed, I would call those "packages" too, but what if the raw materials before packaging are not already formed packages but a large piece of plastic (that somehow the machine folds and seals forming a fully formed "package")
In the original documents (in other language) they are called "packaging paper" but I am not sure what a native english speaker would call it.