The recent preview build of The Witcher 3: Wild Hunt was running at full-HD resolution on PlayStation 4 and 900p on Xbox One.
German website Gamestar attended the recent preview event for The Witcher 3 and examined the three versions that were on offer, PC, PS4 and Xbox One.
Here's the quote, courtesy of Google Translate.
"In the duel console PlayStation 4, meanwhile, has clearly ahead of the graph. Although the textures are a bit more blurred than "high" PC details that falls within the normal TV-distance but hardly noticeable. In addition, the witcher adventure runs on the PS4 in 1080p - but only at 30 frames per second, which did not bother us.
"On the Xbox One Geralt goes also with 30 fps on monster hunt, but only in 900p, the textures also seen slightly more washed out than on the PS4. However, polishes CD Projekt own words yet on the Xbox version, maybe you can still screw up to 1080p, but you would not promise anything. Stand now is the PS4 image the sharper and stronger color."
The game is quite a ways off, and as the quote suggests, the game is still being optimised and the technical specs could very well change, just like we've seen before with Destiny and Diablo 3: Ultimate Evil Edition.