welcomer vs doer

welcomer and doer both are nouns.

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

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

Other hypernyms of welcomer include actor, worker.

welcomer (noun)	doer (noun)
a person who greets	a person who acts and gets things done