Ecosystem names and protocol names are different things
Project V is the ecosystem behind a range of proxy tools and components, with V2Ray as one of its best-known names. Different core and client projects have since emerged in the community, so searches for “V2Ray client” often turn up V2Fly, Xray, and v2rayN as well. These names refer to different layers: protocols describe how communication works, cores implement protocols and routing, and graphical clients help manage subscriptions, settings, and runtime status.
How V2Fly, Xray, and sing-box differ
V2Fly continues community development of V2Ray. Xray grew from related technical foundations and has developed its own protocol implementations and features. sing-box is a separate proxy core project. Their features overlap, but their native configuration formats and supported features aren't identical. Even when names like VMess, VLESS, or Trojan match, check the transport layer, security settings, and how the client generates the configuration. A matching protocol name doesn't guarantee that the full configuration is interchangeable.
What the three open-source clients do
v2rayN, v2rayNG, and v2flyNG all provide their client code as open source. v2rayN is for desktop and brings subscriptions, system proxy, routing, and core operation together in one interface. v2rayNG is for Android and uses the Xray core; v2flyNG is another option built around the V2Fly core. Open source means the code can be inspected and used under its license; it doesn't mean all projects share the same license. Check each project's terms separately.
Client and subscription updates are separate
Updating the client addresses interface, compatibility, and application features. Updating the core affects protocol implementation and runtime behavior, while updating a subscription refreshes remote server details. Rule databases may have their own update process as well. Record your current settings and back up your configuration before upgrading. Afterward, verify your existing connection before trying new features. When troubleshooting compatibility, note the client, core, and server settings—not just that “V2Ray isn't working.”