mailer vs advertisement

mailer and advertisement both are nouns.

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

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

Other hypernyms of mailer include ad, advert, advertising, advertizement, advertizing.

mailer (noun)	advertisement (noun)
a container for something to be mailed	a public promotion of some product or service
an advertisement that is sent by mail
a person who mails something