changer vs doer

changer and doer both are nouns.

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

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

Other hypernyms of changer include actor, worker.

changer (noun)	doer (noun)
an automatic mechanical device on a record player that causes new records to be played without manual intervention	a person who acts and gets things done
a person who changes something