hotsone

if i use drive wiper from the tool box icon it says over 6hrs to wipe the free space so i usually let in run for a while to see!!! and then cancel after about an hour, but if i use the wipe free space in the Ccleaner advanced area it wipes the free space in less than 1 hour, the free space is 28gb using windows 7. any body no why the difference, are they both doing the same function, any advice appreciated, regards john