Is there a way to Distinguish Graphics Cards

What are the difference between all Graphics cards? How do you compare them?
What companies are better than other? anyone know?

well memory is a huge diffrence, as well as core clock speeds, pipelines, and radmac speeds. brands also affect performance, sometimes by just being adverse to the chipset on your motherboard. i use http:www.anandtech.com for comparisons, usually i'll google a game like half life 2 or battlefield 2 if you want high end results and see how cards stack up.

There is a graphics card guide in the guide section for a reason. Have a read and then choose a budget no point us telling you about some £300 cards when your budget is £25.