I think that most people don't understand how much must be done just to get a clean low-distortion signal on vinyl. They think it's all "analog" and therefor "high-resolution" and "linear". The vinyl process is anything but those things. There are so many issues to deal with in just cutting a good master disc, they really have no idea.
Just as one example, the angle of the playback stylus as it sits in the groove is standardized at 15 degrees from vertical, angling downward and in the direction of the record's rotation. For low distortion, the groove should be cut with a stylus that matches that angle, but because it is essentially hinged and cutting a variable depth groove, the actual cutting stylus angle is constantly changing, and lacquer tends to spring back after being cut, so a compromise is made by setting the cutter stylus angle at 18 degrees. The result if this angle misalignment is increased distortion. There are active methods that can add pre-distortion (add inverse distortion) to the groove, but you can't accurately predict the shape of the play stylus (is it conical, eliptical, shibata?) and stylus shape affects contact area, pinch, etc., so that pre-distortion is not always accurate. And that's just one example. The process is fairly loaded with compromises and potential inaccuracies and distortions.
If you get intimate with the entire process and know the flaws and compromises, you begin to see that the fact that vinyl ever sounds good is pretty amazing, but the compromises that impact audio quality in CD-quality digital are far fewer. I've done both, side by side, and produced CDs and vinyl that sounded virtually identical - on the first few plays. You can always pick out the vinyl, though. It wears, it's got surface noise, and it's more distorted on peaks.
But to me, the discussion of the final medium is pointless unless the discussion includes the entire signal flow from master to release, which as noted by bigshot, has to be at least slightly different. Separate the two projects in time, and you've now got different people doing the mastering for CD and vinyl. And the problem with that is, since cutting a master lacquer is quite complex, it required a fairly deep understanding of the process, and required some pretty well trained and educated people. "Cutting" a digital master for CD is a much simpler process, and the breed of people doing that are far less trained. The results often speak for themselves, and that's why some old vinyl releases beat their later CD counterparts. It's not the medium, it's the total process controlled by people. And the people are the biggest variable.
Inverting and differencing two versions is interesting, but which was right? Sort of pointless, except to show one is different from the other.
Edited by jaddie - 1/3/13 at 8:44am