preserver vs doer

preserver and doer both are nouns.

Word	Noun	Adjective	Verb	Adverb
preserver	Yes	No	No	No
doer	Yes	No	No	No

As nouns, doer is a hypernym of preserver; that is, doer is a word with a broader meaning than preserver:

Other hypernyms of preserver include actor, worker.

preserver (noun)	doer (noun)
rescue equipment consisting of a buoyant belt or jacket to keep a person from drowning	a person who acts and gets things done
a skilled worker who is employed to restore or refinish buildings or antique furniture
someone who keeps safe from harm or danger
a cook who preserves fruits or meat