The fakes do make the same whining noise like the originals if not even louder..
I've seen a fake unit. The unit is in polished finishing on the outside while the originals have slightly rougher surface. The printing on the fakes are not totally nice to look at. Uneven embrossed logo and such... however, i suspect those are the earlier imitation units... now, they may have copied externally to about the same as the originals. The fake unit is unable to hold high fuel pressure during high flows.... eg. in a turbo car, when you reached 6k rpm while in full boost, the fuel pressure drops.
To be able to be sure you have purchased the genuine is to do a flow test. The fakes do not flow as much as the originals. Also the pressure test.