Well Trump just flat out lies far more often. Clinton is a typical (non-republican) politician and that means trying to not lie if it can be helped. Put forward stats only from one side - yes. Mislead - yes. But flat out lie in a way that can be easily caught - no - or at least do it as least as possible.
This is why Clinton will be called out rarely if at all for lying, while for Trump its going to be lots of times, or at least enough times to the point where it sinks in that he can't get away with it and so stops.