focal length vs distance

focal length and distance both are nouns.

Word	Noun	Adjective	Verb	Adverb
focal length	Yes	No	No	No
distance	Yes	No	Yes	No

As nouns, distance is a hypernym of focal length; that is, distance is a word with a broader meaning than focal length:

focal length (noun)	distance (noun)
the distance from a lens to its focus	the property created by the space between two objects or points
	size of the gap between two places
	indifference by personal withdrawal
	a distant region
	the interval between two times
	a remote point in time

focal length (verb)	distance (verb)
	go far ahead of
	keep at a distance