These options are only available to the user when the user tries to recover data from a FAT formatted volume.
In the Quick Scan option, the application searches for deleted files and folders using basic algorithm. Now if the results are not satisfactory i.e. files/folders are not found, then use the Deep Scan option. Deep Scan option scans sector by sector and finds deleted files/folders. Deep Scan takes more time but results are better than Quick Scan.