Well not quite.

C is a Booking Class (or fare basis).

J tends to be the AA definition of the cabin of service (like Business = J and First = P on international 3 class equipment). J (Business) can be also seating in the forward cabin of a 2 class equipment when said plane is flow on non-US routing (like international, Canada, Caribbean, Central America, Mexico...)

Other airlines (like UA) may call that seating category C .. it is not as much an 'area' thing as dankyone implies. There is not a real standard within the airline industry about the fare basis codes.

However, within the AA system ... the following fare basis codes will seat in the Business Cabin....(per ExpertFlyer)...

CN AA BUSINESS
D AA BUSINESS
I AA BUSINESS
J AA BUSINESS
U AA Business - Award t
R AA Business - Dom upgrade from Coach using 500 mile Sticker/EXP/Y-B elite on 3 class flights
C AA Business - Upgrade from Coach using Miles/eVIP on all 3-class and Int'l 2-class flights