A319/A320 MTOW differences
Maybe that is a stupid question, but I have been unable to find a reasonable answer...
I understand that there can be different structural configurations, or interior/fuel tank configurations, for a given type of aircraft (for a 320, or a 319...). I think that is what Airbus calls weight variants.
But lets consider the maximum MTOW of each, for instance 77T for a 320 and 68T for a 319: why is it that by cutting a few frames out of a 320 (to make a 319) the maximum MTOW decreases?
Is it linked to specific structural differences, or just due to commercial differences?