blurb vs promotion

blurb and promotion both are nouns.

Word	Noun	Adjective	Verb	Adverb
blurb	Yes	No	No	No
promotion	Yes	No	No	No

As nouns, promotion is a hypernym of blurb; that is, promotion is a word with a broader meaning than blurb:

blurb: a promotional statement (as found on the dust jackets of books)
promotion: a message issued in behalf of some product or cause or idea or person or institution

Other hypernyms of blurb include packaging, promo, promotional material, publicity.

blurb (noun)	promotion (noun)
a promotional statement (as found on the dust jackets of books)	act of raising in rank or position
	the advancement of some enterprise
	a message issued in behalf of some product or cause or idea or person or institution
	encouragement of the progress or growth or acceptance of something