Why does 5D3 look cleaner than D600?

If you go here

http://www.dpreview.com/reviews/nikon-d800-d800e/32

and select the D600 from the menu for one of the cameras, choose ISO 12800 at the top and click on the blue watch at the bottom right where it says "FRIDAY" or on the lady on the Kodak test card, you will notice that the output from the 5D3 is MUCH cleaner.

What's going on? Is there any way to make the output from the D600 look like that? That's one of the first things I noticed when I first started shooting high ISO with my D600. I kept thinking to myself, "Why isn't it smooth?" I played with my friend's 5D3 briefly, and when I examined the photos on my computer, I was amazed at how smooth everything was.

For now, I've set the high ISO NR to high to see if I notice any difference. I'm frankly a little disappointed at the high ISO performance. gasp