P E N C I L
UBS: Ubuntu : add to user group (not by default) AND restart
When run groups, there is "vboxusers"
You can change the Shared Folder and Network type and windows will pickup the new configure immediately
NAT: Guest has it's own network and its ip 10.0.2.2 and net is routed through host (translate address). Guest can access to host IP but host cannot access guest
Bridge: Guest become just a nother machine in the same enterprise network as Host (IP are different but in the same subnet). Guest and host can access ip of each other