That laptop comes with a Geforce 840m GPU with DDR3.
It is an okay CPU. It basically considered to be a mainstream GPU, not a gaming GPU, though it can be used to play games. Due to it's relatively low performance and that fact that it is only using DDR3 RAM (slow compared to DDR5), you would be better off saving some money and going with the 2GB version.
If it was a relatively high performance GPU like the GTX 860m which uses DDR5 RAM, then sure go for 4GB of video RAM. But for the 840m, the extra 2GB DDR3 RAM is a waste of money.