Abaixo segue nota retirada do OsNews:
“Python 3.0 (a.k.a. ‘Python 3000’ or ‘Py3k’) is a new version of the language that is incompatible with the 2.x line of releases. The language is mostly the same, but many details, especially how built-in objects like dictionaries and strings work, have changed considerably, and a lot of deprecated features have finally been removed. Also, the standard library has been reorganized in a few prominent places.” See what’s new in Python 3.0 for differences between 2.x and 3.x.