What’s the difference between Delta Backup & Full Backup?

We request that Microsoft get the list of files modified through the delta link and then use it during the backup process. As we still see errors on the Delta link, we manually run a full backup now. We fetch all files under the OneDrive account at Microsoft through the full backup method and then process the backup. During this process, we will skip files with the latest version and back up only those with changes. We will notify you once this manual method of full backup is completed.