AOR was originally a term for the stations consulted by Burkhart-Abrams and came out of Abrams' success in North Carolina with what many consider the first "AOR" station.That's an interesting point. FM Rock stations were usually classified as Progressive Rock from around 1967 until about 1977 when the term AOR (Album Oriented Rock) took hold.
As the consultancy added more and more stations, that name became widely known as the "Album Rock" format even though what they mostly played were singles releases.