I found this on a site from Google:
High-level formatting (Format) - The process of creating the boot record, the FAT(s), the root directory, and the files area on a disk that has already received a low-level format.
Quick Format - Introduced in later version of DOS, this process will perform only a high-level format of a disk, using the tracks and sectors already defined by an earlier formatting. Quick formatting a disk takes far less time than performing a complete format.