A lot of the CG (ships, etc.) looks sharper to my eye. I didn't notice at first, though, because YouTube defaulted to 720p (and since it's a 1080p render downscaled to be side-by-side, you do need those pixels).

The creator says that 4K-vs-480p renders (that is, rendering the YouTube video at 4K) are on the way.

Same. It's certainly not objectively "amazing" (to use the author's own verbiage)