Comparator Fast will search for duplicates by:
Name, Size and...... the option you choose in this section.
Time: Is the most fastest. It'll search for duplicates by Name + Size + Date and Time. This is the recommended method for speed when searching for duplicates. But is not 100% accurate, because you may have a file with same Name, Date, Time, and Size, but some differences may exists on it's content.
CRC: It takes more time. Comparator Fast will consider duplicates files with the same Name + Size + CRC32.
Data: This is the most slowest option, but the 100% accurate way to find for duplicates. Comparator Fast will consider duplicates only files with the same Name + Size + Content. It means, Comparator Fast will read both files and consider duplicate if their content is exact.
None: Don't search for duplicates. Is the most fastest option for Comparator Fast if you really don't need to get a report of duplicate files.