How many H815 versions there are and how to identify them?

I though that H815 was the european open version (able to unlock bootloader and such) and that the other versions had other names, but I've seen people about talking about H815 versions with the same name and with or without LTE-A, or even specific H815 versions for Asia, France or even non-carrier USA, and on all of them the bootloader is locked as ****.

Is this true? in this case, if you were buying this phone online, how to determine you're buying the european open version? what's the model name exactly for that?

Thanks!