How Project V and V2Fly relate
Project V is an open-source ecosystem built around network proxy tools, with V2Ray as one of its widely used core projects. The V2Fly community continues development and maintenance of the V2Ray core. When you see V2Fly in documentation, focus on its core implementation and supported configuration rather than treating it as a separate subscription service. GUI clients can call a core to establish connections, but interface labels do not always match core configuration fields exactly. When reading a configuration reference, rely on what each field means.
The Xray fork and protocol compatibility
Xray grew from related code into an independently developed core project with its own features and configuration requirements. The two cores share support for some common settings, but that does not mean every transport, security option, and routing field is interchangeable. To determine whether a node will work, check the full set of parameters, not just whether it uses VMess or VLESS. If the server provides specific extension parameters, confirm that the core used by the client supports them. Simply switching to a different GUI may not resolve a compatibility issue.
What the three open-source clients do
v2rayN is a desktop client with a GUI for managing subscriptions, choosing nodes, and configuring proxies. v2rayNG is an Android client that uses the Xray core; v2flyNG is an Android option for users who need the V2Fly core. All three clients are open-source software. The client code and bundled cores are governed by their respective open-source licenses. Open source means the code can be inspected, used, and modified under the license terms. It does not mean every client has the same features or that settings can be copied between interfaces without checking them.
Client updates vs. subscription updates
A client update changes the program and bundled components; a subscription update refreshes the set of nodes provided remotely. Neither replaces the other. Updating a subscription may regenerate node settings you've edited manually. A client update may change where settings appear, their defaults, or which features are supported. Back up your configuration before either change. Afterward, test a known configuration and check routing and DNS behavior. This site organizes client downloads by platform and explains setup steps in its guides. Check the download page for release information and the configuration reference for details on each setting.