The Main difference between “Derived Measure” and “Calculated Measure” is when the calculation is performed. The following tables will help you understand about this.
This is calculated before the aggregation are created
This is Calculated after aggregations are created
The values of this measure is stored in the Cube
This values aren’t stored in the Cube
You can choose any one the measure depends on your requirements. The main purpose for choosing between a derived measure and a calculated measure is not efficiency, but accuracy.