* MA (Master of Arts): This is the more common and widely accepted abbreviation for a Master of Arts degree globally. It's generally the standard designation for graduate degrees in the humanities and some social sciences.
* AM (Artium Magister): This is a less frequently used abbreviation, originating from the Latin "Artium Magister," which literally translates to "Master of Arts." It was historically more prevalent in the United States, particularly at older universities, but is now much less common. In many cases, universities that once used AM now use MA.
In short: While technically the same degree, the abbreviation AM is now largely archaic. If you see AM, you can safely assume it means the same as an MA. However, MA is the far more prevalent and universally understood term.