The .pkg extension serves as a container archive for both consoles, but the internal architecture differs significantly.
In the world of console hacking, the "PS3 to PS4 PKG" story is one of a long-standing quest for backwards compatibility . Because the PS3 used a complex "Cell" processor and the PS4 switched to a standard PC-like architecture, the two consoles cannot natively understand each other's software. This gap led to the birth of creative, often complex, community-driven workarounds. The Official "Bridge" ps3 to ps4 pkg
The dream of natively converting PS3 games into PS4 files is a common pursuit in the modding community, but technically, it is largely considered impossible it is largely considered impossible