Drive spokes are often slightly shorter to account for the offset and dish although same length spokes can be used with some builds... would be best to disassemble the wheel slowly and carefully (do not cut out the spokes) and input the hub and rim dimensions into a spoke calculator to make sure they are exact.

Unlike horseshoes and hand grenades, spoke measurements cannot be close enough if you want a solid build.

With a 120mm hub the offset and dish will be minimal so same length spokes will work fine... newer wheels with wider cassettes have more offset with typical hub spacing and this is where drive side and non drive lengths will have the most variance.

Tandem hubs and speciality hubs are wider and allow for wide range gearing (ie 9 speed) and little to no dish.