All gamefiles match retail, only the EBOOT.PBP seems to have some last minute adjustments regarding region flags and checking system language on SystemInit.
These UMDs were produced before the official release for QA-testing, reviewing up to promotional purposes. Thus some of them having unfinished builds burned to. (Where especially those not meant for the public sometimes having developer options available!) Depending on the region, company and version they might have a unique but different Disc ID compared to the final retail version. In the gaming industry these type of discs are often referred to as 'silvers'.
