The one on the cartridge adds 1 gram but you counter balance it so it does not add to the tracking force. The other is a seperate tone arm with no cartridge it has a carbon brush and a pad to collect what is brushed up. It is similar to a Watts Dust bug, I prefer the AT ones to a Dust Bug.
As far as force from the tonearm brush on the platter it is insignificant, it also has a counter balance so you can adjust the downward force.
On some models they have wire that can be hooked to a ground to work as an anti-static device.
JIm