In amateur astronomy there are clear differences in night vision
detection of faint objects, both in the retina of individuals and in
their brain processing. The sum of the difference is often 1 magnitude,
and can be up to 2 magnitudes (6 magnitudes being a difference of 100x).
I should say that the differences in the retina are just supposed, but I
do know that some people have extra concentrations of rod cells. There
is a whole range of eye seeing abilities with a very few humans having
extraordinary low level light detection abilities. The supposition in
amateur astronomy is that the two are related.
In addition to mere detection, there seems to be a difference in brain
processing too. It takes experience to notice that there is something
truly there. A sketch of the Andromeda Galaxy as first seen, then at
yearly intervals through one's amateur career shows increasing detail,
despite the aging of the eye.
Of course my wife says that I can't see anything unless it is right in
front of my nose!