in many Windows 10 or MDM workshops, we come back to the point that we discuss how clients or devices will be connected with our on premise environment in future. Of course we then talk about Azure Active Directory. Reason enough that we deal with it here once.
In general I can tell you, that all Microsoft Online Services handle authentication via Azure AD (AAD). So whether you are using O365 (Exchange Online, SharePoint Online, etc.) or services from Azure (OMS, Azure Remote Apps, etc.) – the authentication process is always handled via Azure AD.