Within Canada, J is J. I have never seen any discounted business class.

On some european routes there are J2 fares (e.g. YYZ - LHR) which are slightly lower than the J fare, and on which there are no stopover privileges. This is the fare that will be routinely quoted for a non-stop J class ticket.

Occasionally to BDA, the Carribean and Hawaii there are C class fares, which must be booked and ticketed round-trip, with and advance purchase requirement. These usually take about 35% off the fare.

Ex-U.S. UA often sells Monday-Thursday fares across the Pacific at the lower "C1234" fare, but this is rather like the J2 fare, in that it is lower, but still quite heavily priced.