virtualenv => a way of isolating a set of python libraries. 
                Sort of like a chroot for Python libraries.  
                (Python's version of Perl's perlbrew or Ruby's
                rvm)

  pip => Supercedes easy_install, but as this post mentions,
         doesn't cover 100% of the use-cases (just the most
         common ones). Think of it as Python's version of
         Perl's cpanminus (aka cpanm).

  burrito => The README says it all:
                With one command, have a working Python 
                virtualenv + virtualenvwrapper environment

  virtualenvwrapper => A set of shell scripts/functions for
                       working with multiple virtualenvs in
                       development. Basically sets them all up
                       in a central location so that you can
                       do things like:
                          workon my-websight-library-set