A DISTINCT and GROUP BY usually generate the same result, so performance should be the same across both query constructs.
the diff ::
Use “Group by” when you use aggregate query, and “DISTINCT” when you want to distinct values.
Essentially it is just a matter of syntax in this case, the end result should be same.
some people said that “DISTINCT” execute faster than the “GROUP BY”, because GROUP BY performs appropriate sorting before returning the results. CMIIW