vSGA vs vGPU

Hello
I am trying to get a better understanding of vSGA vs vGPU. It is my understanding that for vSGA, at least one GPU cannot be passed through to the VMs and needs to be assigned to the host so Xorg will start. Can you then assign two GPUs to a Guest VM? Please clarify as I am not sure I have a clear understanding of vSGA Profiles and vGPU Profiles.
Jason