By doing a few dummy bookings on AA.com and looking at the fare rules display on the very last page (how inconvenient) I determined that on a transcon the "Essential" end with 2 and the "Plus" fares end with 7.
Those fares have the following (business) restriction:
Code:
TICKETS MUST BE ISSUED BY ELECTRONIC TICKETING. FARES MAY ONLY BE SOLD BY AA AND MAY NOT BE SOLD BY TRAVEL AGENTS.