Graphics card and GPU is the same thing. GPU - Graphics processing Unit.
Still, you won't find a laptop with an upgradeable GPU. Just get a laptop with a decent gpu like - GT 750m ddr5, gt 755m, gtx 765m, gtx 770m , gt 780m, hd 8850m, hd 8870m or any of those nvidia gpus in SLI, and you'll be fine. (those are some of the most popular laptop gaming GPUs)