[hedayet]

Great question! I'd say the biggest difference is the mindset while using it:

1. This isn’t an alternative to messaging apps. Messaging is for active conversations; social networks are for passive catching up.

2. Facebook Groups come with Facebook distractions. Even if you try feed blockers (which are tough even if not impossible on mobile), a single notification can pull you back into the engagement loop. This, on the other hand, is intentionally boring—it does just one job and nothing more.

It’s like having a home-cooked meal vs. eating at a bar. A bar has "everything" a meal at home does-and more-but the atmosphere pulls you in, keeps you there, and changes the experience entirely. Now I might do want to have a meal at a bar once a week for guilty pleasure, but not every night :-)