This article explains in detail the different virtualisation Types as Tibor explained:
The Typical Virtualisation in production / commercial environment is HyperVisor Type 1.
(That is running on our server at Avinton office)
This is the recommended mode of virtualisation
The other kind of virtualisation is like VirtualBox or VMWare Player running our Ubuntu VM.
This Virtualisation is running on top of Windows or MAC OS not directly on HW – that has many disadvantages for example we often see it crash due to lack of resources.