Originally Posted by
greatwall77
Then, may I assume that is no fare difference to pay for a voluntarily change booking? Both are J class.
Rebooking in the same fare bucket does not mean that there would be no fare difference at all.
Fares might be updated anytime due to seasonality, demand, advance purchase requirements, etc... so there might be a fare difference.
It varies on the date, route, and the date you booked the ticket whether if you need to pay a fare difference or not.