When to Use OneDrive and SharePoint

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Both OneDrive and SharePoint help secure your files and let you access them from any device. They also let you collaborate with others on the latest version of a file instead of sending around different copies that become outdated.

Use OneDrive to store:

Your individual work, such as files that include private info.
Early drafts of file that you don't want to see yet, You can move them to Sharepoint later when you are ready to move them available to the team or org.

Use SharePoint (which you can access through Teams Files) to store:

Team Project Files.
Any resources that should be owned by the business or group even if you leave the organization.