What is the easiest way to compare two web pages using python?

First you want to get both web pages. You can use wget, urlretrieve, etc .:
wget vs urlretrieve of python

Secondly, you want to “compare” pages. You can use the diff tool, as Chinmay noted. You can also perform keyword analysis on two pages:

• Analysis of all keywords from the page. for example How to extract keywords used in the text?
• "" - :
  http://pypi.python.org/pypi/stemming/1.0
• , . : http://en.wikipedia.org/wiki/Tf%E2%80%93idf python, : http://wiki.python.org/moin/InformationRetrieval