constraint vs holdfast

constraint and holdfast both are nouns.

Word	Noun	Adjective	Verb	Adverb
constraint	Yes	No	No	No
holdfast	Yes	No	No	No

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

constraint (noun)	holdfast (noun)
the act of constraining; the threat or use of force to control the thoughts or behavior of others	restraint that attaches to something or holds something in place
a device that retards something's motion
the state of being physically constrained