Threads for Teams is described as 'Threads is a platform designed to make work more inclusive by empowering teams to discuss and make decisions at scale' and is a Group Chat app in the office & productivity category. There are more than 100 alternatives to Threads for Teams for a variety of platforms, including Web-based, Android, iPhone, Windows and Mac apps. The best Threads for Teams alternative is Element. It's not free, so if you're looking for a free alternative, you could try Element or Discord. Other great apps like Threads for Teams are Slack, Wire, Threema and Mattermost.
It's pretty much the same concept: threaded conversations for asynchronous communication, it's not as sophisticated as some aspects of Threads, but I like the better contrast for improved readability on Twist, while Threads tries to look pretty (it does), but sacrificing legibility and scanability for the looks.