restraint vs tether

restraint and tether both are nouns.

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

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

restraint: a device that retards something's motion
tether: restraint consisting of a rope (or light chain) used to restrain an animal

restraint (noun)	tether (noun)
the act of controlling by restraining someone or something	restraint consisting of a rope (or light chain) used to restrain an animal
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

restraint (verb)	tether (verb)
	tie with a tether