A feature release is a major software update that introduces a new version number and starts a fresh support lifecycle. In Windows, it is more than a routine patch: it can change the build, enable new features, and reset the clock on security servicing. The term matters because support is tied to the specific release and edition, not just the product name.
From a security perspective, feature releases define how long a system keeps receiving monthly fixes. Once a release reaches end of support, devices on that branch stop getting security updates and become easier targets for attackers seeking unpatched endpoints. Defenders use endpoint inventory and version reporting to find machines still on older releases, verify the exact edition, and move them to a supported build before patch coverage expires.