I have just started using Ubuntu as my first Linux, have a couple of question.

What is the difference between easy_install and apt-get? 
How do I update my packages with packages installed in both these ways?
They are under pythonpath right?
You are confusing two completely separate things.
Aptitude, of which apt_get is one part, is the Ubuntu system-wide package manager. It has packages for absolutely everything - applications, libraries, system utils, whatever. They may not be the latest versions, as packages are usually only updated for each separate Ubuntu release (except for security and bug fixes).
easy_install is a Python-only system for install Python libraries. It doesn't do anything else. The libraries are installed in the system Python's site-packages directory. There are some downsides to easy_install, one of which is that it's hard to upgrade and uninstall libraries. Use pip instead.
what is the difference between easy_install and apt-get