Both artworks linked above are super impressive but,
I instantly know something is CGI because they all share very similar look I named "High Quality Vintage"
- Noisy (which is photorealistic), but noisy unlike old high-tech film cameras, new cheap hipster replicas, cellphones, or DSLRs/SLRs. No camera before or today produced this kind of look.
The noise imho either has to be done correctly with far more unregularity and further image artifacts if it is supposed to simulate old film, or have smeared look of modern demoisacing algorithm from digital sensors.