The diff, comm, cmp, and colordiff commands are among the many ways to compare text files on a Linux system.

The Linux comm command makes it easy to compare a couple text files and determine if they both contain the same lines -- whether the file contents are sorted or not.

Regdiff is a free software that lets you easily compare, merge and sort registry files. You can directly compare reg files with each other or with the local registry values on your system.