arm's length vs distance

arm's length and distance both are nouns.

Word	Noun	Adjective	Verb	Adverb
arm's length	Yes	No	No	No
distance	Yes	No	Yes	No

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

Other hypernyms of arm's length include length.

arm's length (noun)	distance (noun)
a distance sufficient to exclude intimacy	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

arm's length (verb)	distance (verb)
	go far ahead of
	keep at a distance