AAD

https://docs.microsoft.com/en-us/azure/active-directory/

Main components of Windows server Active Directory:

ADDS

ADLDS

ADFS

ADCS

ADRMS

These are driven by:

Identities, Workstations, Network policies, Servers, Security etc and these are exposed by enterprise protocols like – Kerberos, LDAP, Replication, DNS etc.

Main components of Azure Active Directory:

WAAD (individual identities)

WAACS(Windows Azure Access Control Service) – (will federate access from external providers)

AAD limits itself to Identities and are exposed by protocols like REST, various identity protocols.

How is SSO implemented in Azure? What is Password SSO:

https://docs.microsoft.com/en-us/azure/active-directory/active-directory-sso-integrate-saas-apps

• • • Password-based Single Sign-On enables secure application password storage and replay using a web browser extension or mobile app. This leverages the existing sign-in process provided by the application, but enables an administrator to manage the passwords and does not require the user to know the password.
    • Existing Single Sign-On enables Azure AD to leverage any existing single sign-on that has been set up for the application, but enables these applications to be linked to the Office 365 or Azure AD access panel portals, and also enables additional reporting in Azure AD when the applications are launched there.

From <https://social.msdn.microsoft.com/Forums/sqlserver/en-US/134899f4-620a-4078-a80f-ee2ec22c2fbf/difference-between-existing-single-signon-and-password-single-signon?forum=WindowsAzureAD>