Ah, I see! Like I said though, not necessarily a quality difference but a mastering difference. It's not that the mastering isn't made for the album/songs, it's just the target medium of the masters that are different and the nature of the mediums the masters are destined for.

This obviously comes down to the specific album, but from what I understand it is common to have just two masters, one for digital (streaming/CD) and one for analog (vinyl). A huge driver of this is that you CAN take a streaming master and put it on CD but you CANNOT do the same for Vinyl, because of it's physical limitations. A streaming master on CD functions perfectly while a streaming master on vinyl has a good chance to cause the needle to jump tracks and have distortions because of the loudness the vinyl can't handle. That's why maybe only vinyl gets a special master, because the medium demands it.

Of course there is nothing stopping an audio engineer from creating that vinyl master and sending it for the CD and Vinyl!

Not trying to argue merits of either format though, I love and use both. I even stream music (gasp). I'm just an audio nerd info dumping haha