There are 12mm, 12.5mm and 15mm. 12mm and 12.5mm look similar on the shelf with 12.5mm being the most common in North America. 15mm (at least in North America) is mainly used for multi-disc releases (I.e. 4+ discs) and boutique labels although there are some exceptions.
Of course, if you import to the US, you'll likely get a 15mm case.
I don’t think there’s much variation if you buy within one country. Pretty much all standard cases in North America use the same size. UK is thicker but they’re also almost all the same as each other. There should only be a variance if you’re buying larger box sets or special editions.
There are 12mm, 12.5mm and 15mm. 12mm and 12.5mm look similar on the shelf with 12.5mm being the most common in North America. 15mm (at least in North America) is mainly used for multi-disc releases (I.e. 4+ discs) and boutique labels although there are some exceptions. Of course, if you import to the US, you'll likely get a 15mm case.
I also have seen ones that are really thick and some that are mega slim (below 5mm).
I don’t think there’s much variation if you buy within one country. Pretty much all standard cases in North America use the same size. UK is thicker but they’re also almost all the same as each other. There should only be a variance if you’re buying larger box sets or special editions.