A disc game uses "Disc Game" flags. For a PKG to install to the hard drive properly, it often needs to be recognized as "HDD Game" (depending on the tool, some automate this).
: Transfer these PKGs to a FAT32 USB drive and install them via the "Package Manager" on your PS3. Key Feature: ISO vs. PKG how to convert iso to pkg ps3 upd
On PC, download managers or databases sometimes rename update packages to .upd to distinguish them from full game packages. The PS3 system does not recognize the .upd extension, so renaming it back to .pkg restores functionality. A disc game uses "Disc Game" flags