A game can keep the same output resolution while reducing some of the work used to shade its image. Variable rate shading, usually shortened to VRS, is one way to make that trade-off.
Microsoft’s Direct3D documentation describes assigning different shading rates to different areas. Instead of calculating a separate shading result for every pixel everywhere, selected regions can share a result across a group of pixels.
Resolution and shading answer different questions
Resolution describes the image dimensions at a given stage. VRS concerns how densely particular shading work is performed. The two can interact in a game’s rendering pipeline, but enabling VRS is not simply another name for selecting a smaller display resolution.
A developer might spend less shading work in an area where fine detail is less noticeable and preserve more elsewhere. The visible result depends on the implementation, scene and hardware support. It is not a guaranteed frame-rate improvement of a fixed percentage.
Compare a scene you can reproduce
Choose a save point or benchmark with both detailed objects and broad surfaces. Keep resolution, upscaling and other graphics settings unchanged while comparing the VRS option. Look at the same camera angle, then move through the scene; a still screenshot can miss changes that appear during motion.
Record performance and inspect fine texture, edge-adjacent detail and any distracting changes. If the game automatically bundles several features into a preset, note that you are comparing the whole preset rather than isolating VRS.
A setting is useful when its performance benefit and visual result suit your play, not merely because it sounds newer. If you cannot see a worthwhile gain in a representative scene, keeping the clearer-looking configuration is a reasonable choice. The important part is making a controlled comparison instead of changing several rendering options at once.