Diffutils includes four utilities: diff, cmp, diff3 and sdiff.

* Diff compares two files and shows the differences, line by line.
* The cmp command shows the offset and line numbers where two files differ,
or cmp can show the characters that differ between the two files.
* The diff3 command shows the differences between three files. Diff3 can be
used when two people have made independent changes to a common original;
diff3 can produce a merged file that contains both persons' changes and
warnings about conflicts.
* The sdiff command can be used to list diff of two files side by side or
merge two files interactively.

Install diffutils if you need to compare text files.