[Samba] Share Permissions vs. Security

[Marco Shmerykowsky]

Under "Setting up a Share Using Windows ACL's" in the
Sambawiki it states "You should only need to makes changes
to the Security Tab" and that the "Share Permissions
Tab should be set to Everyone:Full-Control,Change,Read.

On my previous setup I had set the "Share Permissions"
to the MS Security Group that was allowed access to
the share.  Everything seemed to work.

Can someone explain the difference between the two
settings?