safety belt vs restraint

safety belt and restraint both are nouns.

Word	Noun	Adjective	Verb	Adverb
safety belt	Yes	No	No	No
restraint	Yes	No	No	No

As nouns, restraint is a hypernym of safety belt; that is, restraint is a word with a broader meaning than safety belt:

safety belt: belt attaching you to some object as a restraint in order to prevent you from getting hurt
restraint: a device that retards something's motion

Other hypernyms of safety belt include belt, constraint.

safety belt (noun)	restraint (noun)
belt attaching you to some object as a restraint in order to prevent you from getting hurt	the act of controlling by restraining someone or something
	a device that retards something's motion
	discipline in personal and social activities
	lack of ornamentation
	a rule or condition that limits freedom
	the state of being physically constrained