According to WABetaInfo, the Communities feature appears to give group admins more power over groups. This includes the ability to create groups within groups, which may be similar to how channels are arranged beneath an umbrella Discord community.
Admins may be able to invite new users via a Community Invite Link and then start messaging other members. It’s hard to tell how exactly these chats might look right now, but WABetaInfo notes that they appear to be end-to-end encrypted.
It also looks like a subtle design change will help distinguish Communities from regular group chats. As WABetaInfo points out, community icons will be squares with rounded corners, a format that WhatsApp mistakenly enabled (and then quickly disabled) in October. There’s no word on when Communities will be officially rolled out.