This difference was discovered when all of the criteria that affect swing speed, the confidence level of the batter or pitcher(s), the type of ball used, etc. were taken into consideration.
Comparison, on the other hand, is not an easy task for either side to undertake because each person possesses a distinct set of talents that need to be taken into consideration when evaluating data.
Comparing is challenging as it requires factoring in an individual's unique set of talents when analyzing data. To summarize, any decent USSSA bat will perform noticeably better than a USA bat by a significant margin.