SharePoint Online is an integral part of Office 365 as it serves as the underlying architecture for OneDrive for Business and Office Online Apps. In addition, Office 365 Groups uses the Sharepoint architecture for its file storage, shared OneNote notebook, and site home page.
While SharePoint Online is a full-fledged instance, IWU is using an on-premise instance of SharePoint to provide you all the features of our MyIWU portal. For information more information on the portal, please see the relevant guide here.
When to use this feature?
The primary use of Sharepoint Online will be through Office 365 groups, Office online apps, and OneDrive for Business.