DickM - it could be different thermostats? Or possible timing differences when the dough has been mixed, and left to stand - either too long or not long enough - depending on the machine.
Tip - try this if you want to double check,
Make up a batch of the same bread in each machine, set & run at the same time. Check which one stops first after mixing - leaving to rise, see which one stops cooking first - pick the machine that makes it best and ditch the other (Or, on second thoughts - see if you can get it replaced!)
Oh, and I sympathise with you re the noise... SWMBO makes a loaf every couple of nights - but leaves the kitchen door open - guess who hears it? Not her!