Usually, no. Laptops are made in a way that almost nothing can be upgraded, save for memory and hard drive. If by chance it is possible, it would require sending it to a workshop that would charge a hefty fee to do so.
For sure. I just did a quick google search of that model number, and that laptop is equipped with Intel HD Graphics 4000. The Radeon 7640G in the HP will perform better.
I believe the HP might be the best choice. Two of them don't list the graphics hardware, and the other one is an APU but a bit less powerful than the HP.