With new technology, comes new and improved features (you would hope so). Here is the one I would say yields the biggest change from Kepler; in NVIDIA’s own words…
DSR (Dynamic Super Resolution:
Our new Maxwell architecture introduces a raft of innovative, exciting technologies that make your games better in dramatic ways. Of these new features, Dynamic Super Resolution (DSR) will have the largest impact, enhancing any game that supports resolutions above 1920×1080. What does DSR do? Simply put, it renders a game at a higher, more detailed resolution and intelligently shrinks the result back down to the resolution of your monitor, giving you 4K, 3840×2160-quality graphics on any screen.
Enthusiasts with compatible monitors and technical know-how refer to this process as Downsampling or Super Sampling. DSR drastically improves upon this process by applying a high-quality filter specifically designed for the task. DSR also makes the process simpler with on/off integration built directly into GeForce Experience and It’s compatible with all monitors, removes the need for technical know-how, and is integrated into GeForce Experience’s Optimal Playable Settings.