A Microsoft file hosting and synchronization service.
Hi Tony B,
Yes, you are right. OneDrive sync and backup are the same. When you sync OneDrive, you backup those files on OneDrive, which means that you can access synced files via other devices.
Note: You can choose which folders to sync/backup via the OneDrive app.
Back up your folders with OneDrive https://support.microsoft.com/help/d61a7930-a6fb-4b95-b28a-6552e77c3057
Let us know if you have any further questions. -Amit