Forum Discussion
I believe sharepoint is the primary service which integrates all services in Office 365 ?
Interesting question, depends on how you are looking at it I suppose. Worth considering the role of Office 365 Groups as well as the cross-application membership service in Office 365. Not sure if these slides make things clearer?
Azure AD can be used for a lot of things depending on the edition and how it's implemented. Here is a bit more specifics pertaining to Office 365 - https://support.office.com/en-gb/article/Understanding-Office-365-identity-and-Azure-Active-Directory-06a189e7-5ec6-4af2-94bf-a22ea225a7a9.
Taking Microsoft Teams as an example, the role of SharePoint and Office 365 Groups are discussed here:
https://docs.microsoft.com/en-us/MicrosoftTeams/sharepoint-onedrive-interact
https://docs.microsoft.com/en-us/MicrosoftTeams/office-365-groups