I am looking for a high resolution camera for fine art prints and the
Sony A7R seems great since it has the same Sensor res as the D800 in a smaller enclosure.

For some reason when I look at sample shots of the A7r at 100% compared to samples of the D800 at 100% and realized that the A7r looks a lot more artificial with it's noise pattern almost looking like bad compression artifacts, where as the D800 noise looks more film like to my eye when judged at 100% full resolution view.

So my question is:

Is the difference in Noise represented by these two sample sets, because of differences in the Sensor or Noise rendering or are there other circumstances that contribute to the different in outcome in this case (Iso / Shutter Speed / Light / Lens / Apparture)

I think it's pretty obvious what I mean. Especially if you compare Faces, Skin and fine Textures, the A7R has a sort of artificial almost phonecam like artifact like noise, while the D800 seems to be very smooth imo.

Would be great if somebody could enlighten me, since I am just judging by Eye and I don't want to go for the D800 if the difference is just because of the lens or some other factor.

*Sample Sets in Question below, please look at the original resolution file at 100%. especially the horse ones of the A7r and the ones of the boy and the man with the gaping earring on the D800.*

A7R Sample

<http://www.dpreview.com/products/sony/slrs/sony_a7r/sample-photos>

D800 Sample

<http://www.dpreview.com/galleries/reviewsamples/photos/1933469/?inAlbum=nikon-d800-review-samples>