Not much! MLA 9th edition is an expansion of the 8th edition with new sections on grammar, writing advice, mindful of inclusive language, expansion endnotes & footnotes, and new guidelines for annotated bibliographies.
Continue: if a DOI is available it is preferred over a URL or permalink.
DOIs should now include the http:// and https://
For general websites, copy and paste from your browser, some will include the www. and some will not. Either is acceptable.
Full URLs are recommended but optional especially for long URLs that are three or more lines long.
You can shorten URLs to the general site if it is excessively long.
Don’t use shortening services such as bit.ly.
Remember, when getting a URL from a library database where you have to log in and is behind a closed paywall; use the permalink or stable URL provided by the database. Do not copy and paste the browser URL.
If an article is issued by season (spring, summer, fall, winter) the first letter is now lower case.
The appendix includes over 30 pages of citation examples listed by publication format.
Shortening University Press publisher name. If the publisher includes University Press, abbreviate to UP. Example, Cambridge University Press would be shortened to Cambridge UP.