direct mail vs advertizing

direct mail and advertizing both are nouns.

Word	Noun	Adjective	Verb	Adverb
direct mail	Yes	No	No	No
advertizing	Yes	No	No	No

As nouns, advertizing is a hypernym of direct mail; that is, advertizing is a word with a broader meaning than direct mail:

direct mail: advertising sent directly to prospective customers via the mail
advertizing: a public promotion of some product or service

Other hypernyms of direct mail include ad, advert, advertisement, advertising, advertizement.

direct mail (noun)	advertizing (noun)
advertising sent directly to prospective customers via the mail	a public promotion of some product or service