ElementTree is a Python library for creating and parsing XML.
Lxml is a full-featured, high performance Python library for processing XML and HTML.
Application speed effective
"Lxml is faster than elementtree but i ve never found an application where the speed boost paid for the hassles of distribution"
from question "Use lxml in Maya 2013?"
"But in general you will find that lxml is faster more effective and has an api which adheres closely to a python standard the elementtree which comes with the python standard library"
from question "HTML Parser In Python without fixing HTML"
"Note please do tell me if lxml is more easy or this elementtree"
from question "Create XML file with python?"
"Lxml -- 100x better than elementtree"
from question "What pure Python library should I use to scrape a website?"