Here is AA's definition of "canceled flight" vs "schedule change"
- If we cancel your flight and do not put you on another flight within four hours, it's a cancellation -- and you are entitled to a refund
- If we cancel your flight and put you on a different flight within four hours, it's a schedule change -- no refund.
Might be useful for others to know about the four-hour rule.
I should add that this four-hour rule seems to be unique to AA. DOT does not specify how significant the delay must be before one is entitled to a refund. In the past, I have had really good experience with both UA and DL to get my money back for schedule changes of 90-120 minutes. AA evidently decided to take the hard line and stick to four hours.
I have no problem with each airline setting their own rules but I feel strongly that the four-hour rule should be disclosed at the time of booking so that people know exactly how to manage their risk. In this case, I would have probably chosen DL if I was aware of the four-hour rule.
The DOT might have a different definition of "cancelled flight" for purposes of the refund rule. But you would probably have to file an air consumer complaint with the DOT to find out.