Quick Scan and Deep Scan

"Quick Scan" and "Deep Scan" are two scan modes of data recovery programs like FonePaw Data Recovery. 

Literally, "Quick Scan" is fast and takes less time than "Deep Scan". When you connect your device to the computer, launch the program, and begin the scanning, the quick scan process will start automatically and ends within minutes. The reason why it performs so fast is that it only scans for certain volumes, lost volumes, or removable media. You can find most of your data through a quick scan. 

However, if you can't find the files you need after the quick scan process, you will need the "Deep Scan". It scans the whole drive to find out more data. Meanwhile, it will take a longer time as well because there is so much data to be scanned. The result of the deep scan process will be more prices and detailed. 

In short, "Quick Scan" will be fast but it only scans on some selected volumes while "Deep Scan" takes longer but more thoroughly.