ADAC can help simplify your day-to-day AD administration work. According to this guide on IT Windows Pro, administrators can use ADAC to perform common AD user, computer, group, and organizational unit (OU) object management tasks.
"ADAC offers administrators a good alternative to the Active Directory Users and Computers (ADUC) Microsoft Management Console (MMC) snap-in for managing AD objects. As with ADUC, administrators can use ADAC to perform common AD user, computer, group, and organizational unit (OU) object management tasks. Like ADUC, the current version of ADAC is used only for managing Active Directory Domain Services (AD DS) instances and not for managing Active Directory Lightweight Directory Service (AD LDS, formerly ADAM) instances.
"The key difference is that ADAC is a very task-oriented administration tool that can help you manage AD in fewer steps. The ADAC interface focuses on key AD administration tasks."