As adjectives the difference between focal and nonfocal
is that focal is belonging to, concerning, or located at a focus while nonfocal is not focal.
focal
English
Adjective
(-)
Belonging to, concerning, or located at a focus
(medicine) limited to a small area
Derived terms
* focal length
* focal plane
* focal point
nonfocal
English
Adjective
(-)
Not focal.