What is the real difference between average performing video card and high end Gpu card?

I have XFX 9800 GT and gonna buy HD 5870. With 9800GT i can play all latest games without lagging and i can see good colors on ,my Dell 24" Full HDD LCD. Other than increase in frame rates in games with highest settings what is the Diff between an avg performing and high end video card like 5870.|||The high end card performs better.|||in fast game play you probably are too busy to really notice the difference, if you are into SIMS or similar gaming then the richness and fine detailing of images are very noticeable. If your satisfied with the card you have and your gaming frame rates are more then enough for your gaming skills then stick with what brought you to the dance|||You may enable options that might work better. The performance increases; compare here: http://service.futuremark.com/hardware/

Radeon HD 5870 supports DirectX 11 so you can play DirectX11 titles like JustCause 2 which you can't play with 9800 GT.|||Essentially, the difference is frame rate. If you are satisfied with the frame rates and image quality with your current graphics card, there's no reason to upgrade.|||Speed. The newer cards will run at a huge "potential" speed increase. Your card might be able to play the latest games, but the newer cards will be able to play them at max settings.|||Thats like asking whats the difference between a Volkswagen and a BMW!