Beautifulsoup4 is a Python library that makes it easy to scrape information from web pages (a version of Beautiful Soup). It sits atop an HTML or XML parser, providing Pythonic idioms for iterating, searching, and modifying the parse tree.
Beautifulsoup4 works with your favorite parser to provide idiomatic ways of navigating, searching, and modifying the parse tree. It commonly saves programmers hours or days of work.
Beautiful Soup is a Python library designed for quick projects like screen-scraping.
You can learn more on the Beautiful Soup website.