0xchat is based on NIP-17 and NIP-29. It’s feature-rich, with support for voice/video calls, Moments (notes), and a built-in eCash wallet.
XChat, on the other hand, is based on NIP-EE (nostr mls) and is designed to be simpler.
The reason we split them into two apps is because they target different user groups. 0xchat private chats lean more toward open — anyone can message you, and conversations can stay synced across multiple devices and clients.
XChat leans more toward private/closed — only people with an invite link can chat with you, and message sync across devices/clients is more difficult.