I don't see much of a difference between the PC and PS4 versions. And if you look closer, there are times where the PS4 version looks better, but most of the time the PC version has finer details.
I also don't see much of a difference between the PS4 and PC version. The PS3 version also looks great as well, so it is not worth it to buy a PS4 to play FF XIV.
I think if the PC version is set to higher a resolutions like 2048 × 1080, 2K, 4K, etc, instead of setting the resolution to 1080P, the PC version of the game would look better.
There are also MODs, hacks, and custom texture packs for PC games which can make games look even better because of custom mods, and hacks made by fans or the game makers to improve the look of the game.
Like how Grand Theft Auto San Andreas and VI has Ultra HD mod for PC