The 12" single has the exact same front and back artwork as the original 7" standard release. While there's also a gatefold 7" release, there is no special release like that for the 12" version.
Out of all the UK 12" releases from Hounds of Love, the 12" sleeve for Running Up That Hill is probably the flimsiest of the lot. It easily damages if you're not careful with it.
The 12" single for Running Up That Hill uses the same blackish/greyish labels and silvery writing as the 7". There are also no messages scratched into the vinyl.