This algorithm compares file data byte-by-byte. It uses three types of blocks:
If two bytes are the same in both files - they will be marked as Matched. Otherwise, they are marked as Different. If one file is larger than another, its excess part is marked as Not Found.
This algorithm is convenient if two files are almost equal and there were no data inserted or removed from them.
This algorithm searches for matched, modified, inserted and removed blocks in both files:
This algorithm has a quality/performance tuning option, specified in the Compare Files Window. If set to “Normal”, it may operate faster, but less accurately, and if set to “Precise”, it may operate slower (sometimes much slower), but will be able to find more matches.
Starting from version 7.21, there is a second implementation of a difference algorithm (called "Difference Algorithm (alternate)"), which should provide more accurate results for closely related files.