promulgation vs announcement

promulgation and announcement both are nouns.

Word	Noun	Adjective	Verb	Adverb
promulgation	Yes	No	No	No
announcement	Yes	No	No	No

As nouns, promulgation and announcement are synonyms defined as:

promulgation and announcement: a public statement containing information about an event that has happened or is going to happen

As nouns, announcement is a hypernym of promulgation; that is, announcement is a word with a broader meaning than promulgation:

promulgation: the official announcement of a new law or ordinance whereby the law or ordinance is put into effect
announcement: a formal public statement

Other hypernyms of promulgation include annunciation, declaration, proclamation.

promulgation (noun)	announcement (noun)
the formal act of proclaiming; giving public notice	a public statement containing information about an event that has happened or is going to happen
a public statement containing information about an event that has happened or is going to happen	a formal public statement
the official announcement of a new law or ordinance whereby the law or ordinance is put into effect