To assist people wanting answers using the search function.
For those that can only look at one turbo when wanting to know the differences the markings on the housing will reveal all.
The R32 turbo has 16v stamped on the compressor cover and is the only comprssor cover used on RB20 turbo's.
The R32 turbo most of the time has the smaller 16v or 04u stamped turbine housing. (some 1993 models have the RB25 21u turbine housing)
The R33 turbo has 45v1, 45v2, 45v3, 45v4 stamped on the compressor cover.
The R33 turbo has 21u stamped on the turbine housing.
The R33 turbo as stated above is larger.