In ArcMap 10.3 - Data Frame Properties - Coordinate System tab - under Current coordinate system, it will list "Authority ESRI" or "Authority EPSG" next to the coord sys definition. Examples are:
- NAD 1983 (2011) California (Teale) Albers (Meters) – Authority ESRI
- NAD 1983 California (Teale) Albers (Meters) – Authority EPSG
In the case of A above, that coordinate system is actually in EPSG as EPSG::6414, so is it listed as "Authority ESRI" in ArcMap 10.3 because that version of ArcMap uses an older copy of the EPSG database before EPSG::6414 was added?