The ps4.cpk is a CPK archive only found in the Playstation 4 version of Persona 5. It has many folders named similarly to the data.cpk, but they contain files that are presumably only compatible with the PS4 version of the game.
The movies, sound, and environment textures are found here, among other things. Unlike the ps3.cpk found in the Playstation 3 version, field textures are now in a new GTX container (which still uses DDS images). Bustups are also in a GNF format from the PS4 SDK.
For a list of directories, see ps3.cpk, as they are the same.