spacing vs tightness

spacing and tightness both are nouns.

Word	Noun	Adjective	Verb	Adverb
spacing	Yes	No	No	No
tightness	Yes	No	No	No

As nouns, tightness is a hyponym of spacing; that is, tightness is a word with a more specific, narrower meaning than spacing:

spacing: the property possessed by an array of things that have space between them
tightness: the spatial property of being crowded together

spacing (noun)	tightness (noun)
the property possessed by an array of things that have space between them	lack of movement or room for movement
the time between occurrences of a repeating event	extreme stinginess
	the spatial property of being crowded together
	a tight feeling in some part of the body
	a state occasioned by scarcity of money and a shortage of credit