How do yo tell the difference in graphics cards?

Is there a grading system in graphics cards? I was browsing through the different graphics cards and I was wondering how you tell the difference between them based on the description? They all seem to say they are the next greatest thing. I could not find a standard on any graphics card to base my guess on it's abilities.

 

http://www.overclock.net/graphics-cards-general/502403-graphics-card-ranking-5th-time-last.html

Up to date and very accurate.

 

But only accurate when you know exactly which version of each card they are referring to there; take a look at (for example) Newegg's current listing of ATI HD 4650 1GB cards or the nVidia GT 240's.

I'm pretty sure that on each of those pages, some cards will outperform others, some might do so by a large margin.

 

This link is pretty useful at seeing the differences in each card and you can then check it against some manufacturers versions that are overclocked slightly (the link to the nVidia cards is just after the chart of AMD/ATI cards) http://www.hardwaresecrets.com/article/131 .

Sam

 

Thanks for the replies. I didn't really find what I was looking for in those links, but it got me motivated to find a site that did have what I was looking for. Here is the links to the 2 laptop graphics cards I was comparing. Both from the same site, which seem to be thorough. The bottom link is to the one that will be in my new laptop.

http://www.notebookcheck.net/Intel-Graphics-Media-Accelerator-4500MHD-GMA-X4500MHD.9883.0.html

http://www.notebookcheck.net/ATI-Mobility-FireGL-V5725.18925.0.html