Actually since the SEC settlement, Elon has been required to have his tweets reviewed by legal. Although he is fighting that requirement, he lost in court about it.I disagree. Press releases are official corporate statements that are vetted by legal and public relations of all companies involved. They usually involve a major announcement like a business deal, expansion, new product etc... They actually carry a lot of weight since there can be legal consequences if the press release makes false statements. Elon's tweets are public statements by the CEO. They are definitely not vetted by legal or public relations. They are usually just his personal musings.
Elon Musk loses bid to end SEC 'muzzle' over tweets
On the other hand, although press releases carry potential liability for publicly traded companies, they generally are not legally required to be reviewed by a legal department (although it may make sense to do so). In fact, ironically, many social media accounts of large companies are managed by a relatively low level employee or contractor and sometimes they go rogue, but there's not the same legal consequences given they don't have an agreement with SEC that tweets must be reviewed by legal.