https://wccftech.com/first-look-at-the-new-threads-messaging-app-by-instagram/

Instagram has launched a new camera-based message app called Threads, which allows users to communicate with their closest friends. The app is based around direct messaging, media sharing and status updates. If you have used Instagram Direct, Threads will seem familiar since it heavily borrows the core functionality of the former. 

Threads is not the only messaging app by Facebook. At the time of writing, Facebook has the following messaging platforms: Messenger, WhatsApp and Instagram Direct. What makes Threads different is that it intends to utilize the popularity of Instagram Direct and restricts it to just your Close Friends list.