Indeed, it's very much the same thing.
I have brought up the similarity to email, but it's been of limited help. I'm hoping that moving posts between topics will become possible at some point, which will allow me to clean things up.
It's already possible to move posts between topics. In the menu for a post, choose to edit the topic, and once you start changing it there's an option to move just the post or move later posts in the same topic.