User blog comment:Kirkburn/Technical Update: August 17, 2016/@comment-1757994-20160817230845/@comment-1824272-20160818045207

The way it was explained to us at Community Connect is that the two Forum systems we have right now (the old ones from years ago and the new ones that look like message walls) are not mobile-friendly and could not be coded to become mobile-friendly. So, Discussions was born.

Down the line, when it gets closer to being out of beta, the current Forums will be ported over to Discussions; kudos will be converted into upvotes, threads will become Discussion posts and replies will become... well, replies.

It's still a beta feature, though, so it's not ready yet for everyone to have and it's still being built with more features. But it's the fuuuutuuuurrrrreeeeee.