The Radeon HD 8760m is more a bit powerful than the nVidia GT 720m. The integrated Radeon HD 8610g is a little less powerful than the GT 720m.
When playing DX10 or DX11 games both the Radeon HD 8760 and HD 8610g will operate in dual graphics mode which will provide a bit better overall performance. However, dual graphics mode only works with DX10 and DX11 games. When playing any DX9 (or earlier) games, then only the integrated Radoen HD 8610g will be used.
Therefore, playing games like Skyrim and GTA IV the HP laptop will only be using the integrated Radeon HD 8610g. But when you play games like Battlefield 4 or Assassins Creed 4, then the laptop will use both Radeon HD 8670m and HD 8610g.