Hi...I am looking at a business Comfort fare that allows 2 changes without charge "within the same fare class". I would like to ask whether such a change would still be free as long as Comfort is available, whether or not the new fare in Comfort is the same. (Maybe I've been spoiled by pandemic-era relaxed rules where I was able to make changes for free irrespective of the current fare.)

If I have to pay the fare difference, why require that the change be within the same fare class? On the other hand, I am seeing significant differences in fare between dates within the same (Comfort) class---one could in principle beat the system by booking a date with a low Comfort fare and then change to the day one really wants to travel in. (I have no intention of doing that, but I am trying to figure out what is really possible.)

Or is "fare class" not the same as Comfort (which is a "fare family" and includes I and D fares)?

Many thanks,