Originally Posted by sb127
As someone else said earlier...I don't think I'd use the BB charger on the RAZR. May not hurt it, but it'd be charging at 50% more current than the RAZR charger.
I don't have a RAZR charger, but I do know electonics. Think of it like this: voltage is PUSHed and current is PULLed. If the specs listed are correct (voltage the same on both), then there won't be a problem. The 5.5volts is being applied by the charger to the phone. The phone determines how much current is drawn. One charger offers 550mA and the other CAN supply as much as 750mA (more robust charger) but will _not_ force more current into the phone. These phones all charge via a standard PC USB port as well, which are only rated at 500mA max, so they shouldn't draw more than that.
Again, assuming both chargers supply the same voltage (5 to 5.5v) and offer at least 500mA of current, then either charger is fine with either phone.
I hope this helpls.