restraint vs fixing

restraint and fixing both are nouns.

Word	Noun	Adjective	Verb	Adverb
restraint	Yes	No	No	No
fixing	Yes	No	No	No

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

restraint (noun)	fixing (noun)
the act of controlling by restraining someone or something	the act of putting something in working order again
a device that retards something's motion	the sterilization of an animal
discipline in personal and social activities	(histology) the preservation and hardening of a tissue sample to retain as nearly as possible the same relations they had in the living body
lack of ornamentation	restraint that attaches to something or holds something in place
a rule or condition that limits freedom
the state of being physically constrained