22.214.171.124.3 Effect on Accounts
Windows domains affect the way that accounts and groups work. Some of this is by convention, and some is by design.
By convention, when a Windows operating system is added to a domain, the domain administrators group is made a member of the local administrators group.
By design, groups have different scopes when domains are involved. Groups can be defined as globally known and therefore usable by other domains, or known only within the domain in which they are defined.