Maybe AW looks much better in SP, I don't know, haven't tried that yet (I'm not interested in COD campaigns). In MP, though, Ghosts has a clearer, sharper image, and the colors are much more vibrant and appealing, although I realize that the latter has a lot to do with art design.
Still, often is it said that Ghosts looks like a last-gen game, and that is simply not true. Ghosts is a very visually appealing game at 1080p on the PS4, too bad about the unstable framerate (for that alone AW deserves to be put over Ghosts tech-wise, admittedly). Strictly speaking about visuals, though, I do consider Ghosts and AW to be pretty much on the same level, with Ghosts having the edge, if anything. The notion that AW is "next-gen looking" while Ghosts is not is ridiculous.