This can be very tricky and it will be up to you to map out the values and how they relate to the PS3 values.
You should start by taking a look at a ps3 db that has been setup and has at least one item with categories and options. I think this would be the way to go about it. The db for ps3 has a few things going on with it and if the values do not match up correctly you will not be able to get the data to work.
In your specific question the difference between PS3_Categories and PS3_productcategories is that one holds the categories themselves, and the other is a linking table to associate the categories with the products.