confirmation of Difference between Homegroup & Netbios

Hey!
Due to my problem with the setting of the Network Location of the Host-Only-Adapter from Sun's Virtual Box, I was toying around with the networkdevive itself.
Found the option "Activate Netbios over TCP/IP"
I thought I knew that one, so I turned it on an hurray, I had access to samba running on the linux running on the Virtual Box.

So I'm confused, what is the difference between homegroup and Netbios?
Is Homegroup some sort of mutual access without proving credentials?
E.g.
You are in my homegroup so I trust you with all I got in my share and I'm willing to access your share as well?
Whereas netbios is only a one-way-access,involving authentication?

//edit
Thanks for moving.

Netbios over TCP is how Microsoft systems do Computer Name to IP Address mapping and Name resolution. NetBIOS has been around along time and is really a legacy protocol. As far as I know NetBIOS over TCP is only supported by IPV4.

Homegroups is a new system by Microsoft that provides file and folder sharing and other functions via IPV6 and only works between Windows 7 systems.

NetBIOS is a protocol and HomeGroup is a Windows Security Group.