Standard scan (Neither SmartScan nor StrongScan is selected)
A standard scan looks for files deleted using a standard Windows method, such as files deleted by a right-click menu selection. If you inadvertently deleted a file, this will be appropriate for most uses.
SmartScan
The SmartScan® technology eliminates irrelevant and useless junk files from scanning, making it faster and easier for you to find the files you need. If you inadvertently deleted a file, this will be appropriate for most uses, and will be faster than a standard scan.
Strong Scan
If a file was deleted or lost because its parent disk was formatted or corrupted, a standard scan may not recognize the file. With StrongScan® you can perform a deeper scan to find and reassemble data. StrongScan checks your hard drive, CD, DVD, or other removable device - sector by sector. Since it scans every sector to recognize file type patterns (and one gigabyte can consist of over two million sectors), a StrongScan does take more time to process than a standard scan.
Note: You can use a StrongScan and SmartScan together, thereby only performing a sector-level search on relevant files.