Speeding is defined as exceeding a posted speed limit, which may or may not have any relation to the safe speed of the roadway. Bad driving could include speed that is too fast for conditions, tailgating, unsafe lane changes, running red light, failure to yield right of way, and many other problematic actions.
Driving badly is more likely to cause someone to be killed, or injured. If you consider that speed greater than safe can be considered driving badly, then every incident that includes excessive speed is also part of driving badly. Other things are also considered driving badly, so the total of bad driving incidents will always be greater than or equal to the incidents that are only involving speed.
It would be like asking which has more deaths, motorcycles or motor vehicles. Seeing as a motorcycle is a motor vehicle, the total deaths for motor vehicles will include motorcycle deaths. Therefore the total for motor vehicles can never be less than the total for motorcycles.
If you are asking if exceeding a posted limit is more likely to cause a fatality than bad driving, the answer is no. Speed limits are based on many factors, not all of them safety related. may political factors can go into speed limits being set artifically low, from a safety standpoint!
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