signatory vs signer

signatory and signer both are nouns.

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

As nouns, signatory and signer are synonyms defined as:

signatory (noun)	signer (noun)
someone who signs and is bound by a document	someone who signs and is bound by a document
	someone who can use sign language to communicate