From what ive read, the series 2 r32 (1991-1993) had factory side intrusion bars installed into the doors.
Any series 1 r32 imported into australia, gets the bars fitted in during compliance, so in the end there is no weight differences.
The series 2 has different steering wheel design, different fabric, different colour dash fascia and different plastic interior (bumpy instead of smooth).
Plus other small little bits, but all these changes wouldnt affect greatly the overall weight of the car.