Azure AD provides secure single sign-on for various devices and applications, managing and storing credentials in the cloud, and user reporting and controlling, without using servers in your office.
Azure Active Directory is a cloud service that provides Identity as a Service (IDaaS), authentication, authorization, and identity management functions for the company's cloud and enterprise systems.
Downtime status: users need to restart their PCs and log on to the newly created accounts. Profile settings and documents are not migrated.
The plan may vary depending on your needs.