the 110v is mainly used for site work generally used with a step down transformer 240 to 110v plugged into the mains or fed from a 110v transformer supplied by the site
a 240 v version can be used on site as well as long as the cable is armoured and the unit is rcd protected at the power source
generally the shock if recieved from a 110 system is lesser than that of one recieved from a 240 unit
but it still tingled around the old heart when you get one
the 110v is the safer option but you will need a transformer or generator with a 32amp outlet to run it
hope that helps