Why does my PC have 4 graphics adapters?

I bought a Fujitsu Lifebook AH532 laptop yesterday. Before buying it, I was told it has a GeForce GT640 graphics card installed, but when I started it and ran AIDA64 it showed me 4 graphics adapters, 3 from Intel and 1 from nVidia.

I then ran a benchmark in GTA IV, and the used graphics device was Intel's, not the nVidia.

What does it mean to have 4 adapters, and how do they function?

Your laptop has 2 hardware GPU chips - Intel HD Graphics 4000 and the Nvidia GT 6400.

As you pointed out the driver will switch in between based on performance requirements.

What you see in the control panel are all of the virtual instances running. I believe each one is assign to an output:

1x HDMI 1x VGA 1x WiDi (Intel wireless Display for connecting to TVs)