The 3350/3357 are model numbers; the numbers are mostly arbitrary to Breguet's own naming nomenclature. Does it really matter why BMW calls their car a 5-series? Why didn't they chose a name like 55 series or AA-series? Why does Audi call their car an "A6" instead of a "F6" or some other combination of letters and numbers? Why are my airline flight numbers the flight numbers they are?