Accrescent's catalog is maintained by a respected community member and checks dev signatures on a third-party database on Github. Correct me if I'm wrong.
While zap.store currently is more or less that, we're aiming to change the status quo trust model.
Users will be able to cryptographically verify an artifact came from a developer using nostr. They can do so directly, relying on a web-of-trust check, or indirectly via curators (choose your own walled gardens).
In addition, we're targeting multiple operating systems and other features like relay-based communities, the ability to zap apps and developers, a marketplace for new apps and more.
The big difference is that once developers start signing their own apps, and using different relays (we're a few months away from that), there effectively is no centralized walled garden. No other app store doing that. Does that help?