DiffUtils
show differences between files
You can use the diff command to show differences between two files, or each corresponding file in two directories. diff outputs differences between files line by line in any of several formats, selectable by command line options. This set of differences is often called a `diff' or `patch'. For files that are identical, diff normally produces no output; for binary (non-text) files, diff normally reports only that they are different.
You can use the cmp command to show the offsets and line numbers where two files differ. cmp can also show all the characters that differ between the two files, side by side.
You can use the diff3 command to show differences among three files. When two people have made independent changes to a common original, diff3 can report the differences between the original and the two changed versions, and can produce a merged file that contains both persons' changes together with warnings about conflicts.
You can use the sdiff command to merge two files interactively.
System
http://gnuwin32.sourceforge.net/packages/diffutils.htm
Diff
Diff: find differences between two files
In the simplest case, diff compares the contents of the
two files from-file and to-file. A file name of -
stands for text read from the standard input. As a spe-
cial case, diff - - compares a copy of standard input to
itself.
Cmp
Cmp: compare two files byte by byte
Compare two files byte by byte.
Diff3
Diff3: compare three files line by line
Compare three files line by line.
Sdiff
Sdiff: side-by-side merge of file differences
Side-by-side merge of file differences.