Mastodon and Nostr are decentralized social networks with different characteristics. Here are the main differences:

1. Network structure

Mastodon: It uses a federated network model, where independent servers (called "instances") communicate. This allows users to be part of a network of interconnected communities, with each instance with their own moderation policies.

Nostr: Adopt a Peer-to-Peer (P2P) network model, where each user uses a private key connected to a customer service (such as Iris, Damus, Amathyst, etc.) to send messages to a Relay, which propagates them to the network. This allows users to connect to different relays or use different customers, maintaining their identity and history of activities.