Under the hood, everything looks different, even the oil filter housing angle. I'm sure there are similar components, but given the number of 535d's in circulation now, I haven't read many complaints with the EGR, DPF, urea injection system, NOx sensors, CBU, etc. Its a heavier car and some believe problems occur less often under heavy load.
The car itself has lower power numbers for HP and torque, but even 300-400 lbs heavier it out-accelerates the 335d here in the states and mine gets significantly better fuel economy. This could of course also be from the ZF 8 speed in the f10.
The engines sound different too - the f10 has a more "diesely" sound while the e90 seemed more aggressive and lacked the clickety clack of a traditional diesel.
During the NA e90 335d production, the engine computer design and programming went through at least three major changes, making the f10 diesel seem to be a final result.
TM