From a quick online scan by a layperson, the main difference is the radiopharmaceutical used for tracing. Studies have focused mostly on Ga-PSMA-11, but there are others, listed here:
https://en.wikipedia.org/wiki/PSMA_scan#Radiopharmaceuticals
Since PSMA-PET scans are so new, this is somewhere that it would really pay to talk to an expert at a major research centre. A lot of the online info is out of date (for example, the Wikipedia article doesn't recognise that Health Canada approved Ga-PSMA-11 in October 2022).

Best wishes!