Take a look at some screens from the 2013 version.
http://www.gamersyde.com/news_images_of_the_witcher_3-13837_en.html
Textures were lower res in many places, character models for main characters, NPCs, and horses, were much less detailed.
What was leaps and bounds better was the lighting, particles, reflections, water, LoD, Draw Distance, and possibly vegetation density.
I expect when I go to that exact spot in the PC version, Ultra settings, the assets will be every bit as detailed as that 2013 screen.
I think you are mistaking the sharpening filter for asset detail.
The engine in 2013 was really awful.
It has improved a lot I don't think we can call it downgrade
Right now we have the PC 2014 version with an updated engine and assets vs the inferior release PS4 versione based on the same engine with lower quality assets and settings.
I expect a downgrade but a small one.