signatory vs endorser

signatory and endorser both are nouns.

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

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

signatory: someone who signs and is bound by a document
endorser: a person who transfers his ownership interest in something by signing a check or negotiable security

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

signatory (noun)	endorser (noun)
someone who signs and is bound by a document	someone who expresses strong approval
	a person who transfers his ownership interest in something by signing a check or negotiable security