tightening vs take-up

tightening and take-up both are nouns.

Word	Noun	Adjective	Verb	Adverb
tightening	Yes	No	No	No
take-up	Yes	No	No	No

As nouns, take-up is a hyponym of tightening; that is, take-up is a word with a more specific, narrower meaning than tightening:

tightening: the act of making something tighter
take-up: the action of taking up as by tightening or absorption or reeling in

tightening (noun)	take-up (noun)
the act of making something tighter	the action of taking up as by tightening or absorption or reeling in
	any of various devices for reducing slack (as in a sewing machine) or taking up motion (as in a loom)