In the first case there is a full backup or restore of the archive. If the file already exists with the same name in backup folder, it will be overwritten without any analysis of the creation or modification date in full backup mode. A full restore of the archive is made similarly. But in this step hash sum can be verified. If the hash does not match the sum of the file, file is not transferred to the archive.
A partial backup or restore is made by a different way. Only new files processed in partial backup mode , i.e. those that do not exist in the backup. If the file already exists in backup folder, it is not overwritten, regardless of the date of creation or update. This mode allows you to save time, but you need to use it only in that case if the old files were not changed. In case of partial restore restores only files that are not in the archive. Analysis of the date of the change is not made, and files with an earlier date are not overwritten.
So, if you do not allow yourself the re-editing files after their placement in the archive, you can use modes of partial backup and restore. In all other cases, you must use the synchronization mode.