signatory vs attestator

signatory and attestator both are nouns.

Word	Noun	Adjective	Verb	Adverb
signatory	Yes	No	No	No
attestator	Yes	No	No	No

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

signatory: someone who signs and is bound by a document
attestator: (law) a person who attests to the genuineness of a document or signature by adding their own signature

Other hyponyms of signatory include cosignatory, cosigner, cosigner, abhorrer, endorser, indorser, attestant, attestor, witness.

signatory (noun)	attestator (noun)
someone who signs and is bound by a document	(law) a person who attests to the genuineness of a document or signature by adding their own signature