The main difference between AAD Plan 1 and AAD Plan 2 is the ability to implement Privileged Identity Management (PIM). The second AAD Premium plan is known as “Plan 2” and is included in O365 E5 or M365 E5.
The first ADD Premium plan is known as “Plan 1” and is included In O365 E3 or M365 E3. Two of the editions are considered “Premium”.
There are four editions of Azure Active Directory (AAD).