A big difference is that Secure Scuttlebutt uses a blockchain (the “log”). An app keeps one's own entire log + the entire log of every contact within the “hops

A big difference is that Secure Scuttlebutt uses a blockchain (the “log”). An app keeps one's own entire log + the entire log of every contact within the “hops circle” (hops=1: friends, hops=2: friends + friends-of-friends, …).