The PRS file is the compressed version used by the game. The BIN file is the decompressed version that you have to edit. The PRS edition of the tool probably just decompresses and compresses the file on its own, so you don't need an external PRS tool.
The version that uses PRS has some missing (or deactivated) stuff and idk, according to some people... I saw in several places people saying to use the bin version.
I don't recall what checks the ship does on items, but you'd be better just exporting any change to the ship param .ini files (for the current release of the server).
I just use to edit a version (.bin)
but if you prefer to use versions (.PRS) and (.bin) you need to edit the two files.
I just edit the (.bin) and then use the (PSRU) to convert to (.PRS)
remembering that if you are editing, remember that everything you enter the (item.prs) only will be accepted by ship if you edit the folder (paran). this includes you edit (.ini) inside the folder (paran).
this is the main cause of (god equip) incompatibility of files
agradecimentos a toda equipe de desenvolvedores do Ephinea e do pioneer2. especialmente a Tofu e Sodaboy.....