Reason behind the clarity
There can be too many factors involved to properly answer your question. One is the image quality of the source footage, there are objective and subjective parameters influencing this. Examples:


proper lighting
set design
image framing


Etc.

Then there are technical parameters in the image aqcuisition involved:


quality of the cameras sensor
quality of the post production (grading etc)


Then there are parameters in the delivery:


delivery Codec
compressibility of the images


As for the "subjective" parameters, there are a lot of psychological things involved: a lot of people consider these things as "better" while really only being a matter of taste:


sharpened image
enhanced contrasts
less grain


So unless being more specific, your question IMHO cannot be answered.