I wasn't sure myself so i did a quick Google. This is from a radio controlled model race care forum so the scaling to industrial robotics may be different but it will give a start in your investigation:
"Brushless motors better than brushless motors, but are more $$$ and work
BLDC(BRUSHLESS) motors offer several advantages over brushed DC motors, including more torque per weight, more torque per watt (increased efficiency), increased reliability, reduced noise, longer lifetime (no brush and commutator erosion), elimination of ionizing sparks from the commutator, and overall reduction of electromagnetic interference (EMI). With no windings on the rotor, they are not subjected to centrifugal forces, and because the windings are supported by the housing, they can be cooled by conduction, requiring no airflow inside the motor for cooling. This in turn means that the motor's internals can be entirely enclosed and protected from dirt or other foreign matter.
One of the disadvantages of the brushless system is that it requires a higher technology speed control..
With brushed motors speed is directly related to voltage, and can even be controlled mechanically with a potentiameter or MSC
With brushless no such luck... Speed is controlled through a high speed electronic switch ...
This is part of the reason you get cogging at low speeds with nonsensored bl motors... You are actually watching the switching....."
This is from a radio controlled model race care forum so the scaling to industrial robotics may be different but it will give a start in your investigation.