refusal vs repudiation

refusal and repudiation both are nouns.

Word	Noun	Adjective	Verb	Adverb
refusal	Yes	No	No	No
repudiation	Yes	No	No	No

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

refusal: the act of refusing
repudiation: refusal to acknowledge or pay a debt or honor a contract (especially by public authorities)

Other hyponyms of refusal include prohibition.

refusal (noun)	repudiation (noun)
a message refusing to accept something that is offered	the exposure of falseness or pretensions
the act of refusing	rejecting or disowning or disclaiming as invalid
	refusal to acknowledge or pay a debt or honor a contract (especially by public authorities)