mailer vs worker

mailer and worker both are nouns.

Word	Noun	Adjective	Verb	Adverb
mailer	Yes	No	No	No
worker	Yes	No	No	No

As nouns, worker is a hypernym of mailer; that is, worker is a word with a broader meaning than mailer:

Other hypernyms of mailer include actor, doer.

mailer (noun)	worker (noun)
a container for something to be mailed	sterile member of a colony of social insects that forages for food and cares for the larvae
an advertisement that is sent by mail	a person who works at a specific occupation
a person who mails something	a member of the working class (not necessarily employed)
	a person who acts and gets things done