The IFM feature for promoting domain controllers leverages the fact that the contents of the Active Directory database and the Active Directory SYSVOL are largely identical throughout all domain controllers within the domain. The domain controller cloning feature takes this one step further, and leverages the fact that all domain controllers are largely identical; not just the Active Directory-related files, but all operating system files, most agent installations, information security measures, and most configuration items.
When a domain controller is properly prepared and promoted, it can serve as a template.