Difference between graphic cards on a gaming laptop. Which one is better?

I´m looking at a Asus G73JH-A1 that comes with an ATI 5870 graphics with 1 GB GDDR5
And a Asus G73JW-XA1 that comes with Nvidia GTX 460m graphics with 1.5 GB GDDR5.
Other than the graphic cards those two laptops are pretty much the same. So my question is, Is there a big difference between those two? The only answers I get are from people that you could say are “fanboys” from one company or the other and get into some technical things that I can’t keep up with the conversation. Same thing goes on forums. Please help.