If you're using a RedHat derivative that utilizes yum as it's package manager, you can use the `whatprovides' command to see what package provides a specific file.
yum whatprovides /usr/bin/vim
... grab a coffee ...
vim-enhanced.x86_64 1:6.3.046-0.40E.7.cent base
Debian derivatives provide a similar functionality via the apt-file package.
# sudo apt-get install apt-file
# sudo apt-file update
$ apt-file search /usr/bin/diff