undoer vs ruiner

undoer and ruiner both are nouns.

Word	Noun	Adjective	Verb	Adverb
undoer	Yes	No	No	No
ruiner	Yes	No	No	No

As nouns, undoer and ruiner are synonyms defined as:

Other synonyms of undoer include destroyer, uprooter, waster.

undoer (noun)	ruiner (noun)
a person who destroys or ruins or lays waste to	a person who destroys or ruins or lays waste to
a person who unfastens or unwraps or opens
a seducer who ruins a woman