PS2 Doubts about SLUS-XXXXX game code

[Near]

I have a Bully here on the shelf, and I noticed that it has the acronym SLUS-21269P on the side of the case, however I have another Bully, which is a little old and doesn't work, but its case just says SLUS-21269 without the letter "P" at the end, can anyone tell me what this letter means? The two games are exactly the same, in codes, CD, inserts, why does this version have a P? detail that on the game CD the code is without the letter P

 

[Colek]

https://gamefaqs.gamespot.com/ps2/928128-bully/data

It's from Collector's Edition.

 

[Near]

https://gamefaqs.gamespot.com/ps2/928128-bully/data

It's from Collector's Edition.

Okay but what's the difference? Because I have the normal version and they are literally the same, even on the CD there is no letter P.

 

[Colek]

Nothing is different with the game itself.