The main difference between Reddit and Threads is the length and formatting possible for posts. Reddit of course has no limit, but Threads is inspired by Twitter, of course, and Twitter historically did 140 characters and now 280. Threads’ limit is 500. Then, Reddit has subs/communities of course while Twitter is focused on following users and hashtags. It’s a somewhat subtle difference but is significant. So, all Meta would have to do to make Threads like Reddit is to have a system for communities, and relax the length limit. (I don’t actually believe they’re interested in that, btw).
Algorithms for feeds actually do change a fair bit over time. For instance, YouTube’s has changed a lot and used to recommend a lot more new things based on what other people who watched a video also watched, and now it recommends a lot of videos you already watched. Facebook went to a lot more ‘a friend of yours liked’ type posts. Twitter did too, apparently. I wouldn’t be surprised if they use the IG algo as a starting point but adapt it to Threads over time.
