In a glow discharge process, electrons are more mobile, whereas the positive are less mobile as they are relatively heavy.
This is also in fact, the main reason that in rf sputtering when we are sputtering an insulating target under rf fields, the oscillating electrons hit the target more number of times, and thus leave a net -ve bia potential, so that the less mobile/ heavier ions in the plasma are able to come and bombard the insulating target looking the negative potential left by the electrons, and one is able to sputterng the insulating targets.
In a glow discharge, the difference between average speed of ions and electrons is the bigger the lower the pressure is. At low pressures, the factor is tens or more. E.g., in Nitrogen, T(electron) may easily reach 2-3 eV (20-30 000 K) while T(ions) will be ~1000K.