Windows 2008 server has two groups, security and distribution. Distribution is used for email. So I would say Security makes sense.
The main group type found in active directory is the security group.
Universal group
Access token
Linking
Policy weakness
Active Directory Recycle Bin is a feature that helps minimize directory service downtime by enhancing your ability to preserve and restore accidentally deleted Active Directory objects without restoring Active Directory data from backups, restarting Active Directory Domain Services (AD DS), or rebooting domain controllers. When you enable Active Directory Recycle Bin feature, all link-valued and non-link-valued attributes of the deleted Active Directory objects are preserved and the objects are restored in their entirety to the same consistent logical state that they were in immediately before deletion. For example, restored user accounts automatically regain all group memberships and corresponding access rights that they had immediately before deletion, within and across domains. Active Directory Recycle Bin is functional for both AD DS and Active Directory Lightweight Directory Services (AD LDS) environments. Mohannad Hamid
Domain Group Policy is an infrastructure inside of the Microsoft Windows operating systems (Windows Server 2000, 2003, and 2008, along with Vista) that allows the administrator to implement specific configurations for both computers and users. This infrastructure is what provides the centralized management and configuration for an Active Directory environment. Group Policy provides directory-based desktop-configuration management. With Group Policy, you can specify policy settings for registry-based policies, security, software installations, scripts, folder redirection, Remote Installation Services (RIS), and Internet Explorer maintenance. Admins use Group Policy to define specific configurations for groups of users and computers by creating Group Policy settings. These settings are specified by the Group Policy Object Editor tool and contained in a Group Policy object (GPO), which is in turn linked to Active Directory containers, such as sites, domains, or OUs. Domain Group Policy is the configuration of groups and users within a domain. In this way, Group Policy settings are applied to the users and computers in those Active Directory containers. Admins can configure the users
Group Policy Management Console
Group Policy Management Console
Access Token
Domain Users.
Are you wanting to add a Mac to your Windows Active Directory domain? Is that what you mean by workgroup?