PSAs and broadcast releases have almost nothing in common -- except that each is written for radio, and each fits on one page. Public service announcements are openly promotional pitches, submitted to radio broadcasters in the hope that they'll be aired as a public service. Broadcast releases, like other press releases, are news items, to be treated journalistically (objectively), with a strong news angle (and yet, also, an eye for entertainment value -- an important consideration for broadcasters.) There are also format differences.