press release vs announcement

press release and announcement both are nouns.

Word	Noun	Adjective	Verb	Adverb
press release	Yes	No	No	No
announcement	Yes	No	No	No

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

press release: an announcement distributed to members of the press in order to supplement or replace an oral presentation
announcement: a public statement containing information about an event that has happened or is going to happen

Other hypernyms of press release include promulgation.

press release (noun)	announcement (noun)
an announcement distributed to members of the press in order to supplement or replace an oral presentation	a public statement containing information about an event that has happened or is going to happen
	a formal public statement