Active Directory Rights Management Services is a role which can be activated within any server 2008 or 2012 product. When deployed, the powers of IRM is unleashed.
We use AD RMS mainly as part of our On-Premises solutions.
The biggest difference between the Cloud Solution (Azure RMS) and On-Premises (AD RMS) is that AD RMS requires Active Directory Federation Services (AD FS) and a trust configured to share files securely between external organisations.
Click here to find out more how ADRMS works
Click here to find out more about Federation Services