Fully flexible:
"Changes
Time/date changes permitted at any time before each flight departure for a change fee of $ 70 or an upgrade fee of $ 70 plus any difference in fare. Changes subject to availability. Fees apply per ticket
If you want to cancel your flight
If the booking is cancelled before your first flight, a cancellation fee of $ 100 per ticket applies"

cheapest:

"Changes
Time/date changes permitted at any time before each flight departure for a change fee of $ 70 or an upgrade fee of $ 70 plus any difference in fare. Changes subject to availability. Fees apply per ticket
If you want to cancel your flight
If the booking is cancelled before your first flight, a cancellation fee of $ 100 per ticket applies"

I don't understand what the difference is, except of course tier points, that raises the cost of the fully flexible ticket so much. The conditions seem quite the same.

Please enlighten me!