endorsement vs promotion

endorsement and promotion both are nouns.

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

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

endorsement: 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 endorsement include packaging, promo, promotional material, publicity.

endorsement (noun)	promotion (noun)
the act of endorsing	act of raising in rank or position
formal and explicit approval	the advancement of some enterprise
a promotional statement (as found on the dust jackets of books)	a message issued in behalf of some product or cause or idea or person or institution
a speech seconding a motion	encouragement of the progress or growth or acceptance of something
a signature that validates something